Solenoid Replacement – Why It Fails, And How Much To Replace It?

One of the most complicated parts of any car isn’t, perhaps rather surprisingly, the engine. I’d say that honor goes to the transmission, the very component responsible for translating your engine’s myriad of explosions, into usable power. Crack open a gearbox, and you can find a vast maze of valves, gears, pumps, clutches, shafts, and more. Hence, why a solenoid replacement can be quite complicated.

The transmission or ‘shift’ solenoid, after all, is what’s chiefly responsible for controlling the circulation of hydraulically pressurized transmission fluid. Otherwise known as “gearbox oil”, this fluid is essential for your transmission to function. Without its fluids, your car’s transmission would not only fail to shift and change gears. In addition to that, it’s deprived of its key source of lubrication and cooling, too.

Whenever you bring a car to the workshop, with some gearbox-related gremlins with it, the solenoid is often mentioned by the mechanic. But how is it that your shift solenoid could fail? Crucially, how much would a transmission solenoid replacement cost, and what would such a task entail? If you’re ready to get your car back up and running again, here’s all you need to know about a solenoid replacement…

• What Is A Shift Solenoid?
• How Does It Work?
• Symptoms
• OBD Codes
• Replacement Cost
• Prevention
• Final Thoughts

What Is A Transmission Solenoid, Anyway?

As we’re trying to wrap our heads around what a solenoid replacement is, why not discuss the part in question… So, what’s a transmission or shift solenoid, in the first place? As we highlighted earlier, the primary role of the transmission solenoid is to control the flow of transmission fluid. The solenoid itself is an electro-hydraulic or electromechanical valve, which can be kept opened or closed when needed.

Some technicians also refer to it as a “solenoid pack”, as there your transmission has several different solenoids working together. The most important types are the (aforementioned) shift solenoid, lockup solenoid, and transmission control solenoid. Regardless, they all open and close – thus allowing the transmission fluid to circulate accordingly – based on input from your vehicle’s computer brain.

More specifically, the ECU (engine control unit) and the TCM (transmission control module), which can determine – based on input from various sensors dotted around the car’s powertrain – as to the correct moment and gearing to shift into. Typically, these computers and sensors gauge the velocity that your car is traveling at. Subsequently, sending electrical signals to the solenoids to let gearbox fluid flow.

Transmission solenoids are exclusively found in automatic gearboxes. That pressurized gearbox fluid is vital to the workings of a transmission. Hydraulically pressurized fluid – permitted to flow by your car’s solenoids – is the one engaging and disengaging the various parts of the transmission. Examples may include its gear sets, brake bands, and clutches. Without that pressure, your gearbox won’t function.

How Does A Transmission Solenoid Work?

However, it’s not just the ability of your gearbox to function that is reliant on a solenoid replacement. If the solenoid is faulty, the transmission fluid pressure might be off, and this can impact performance, as well. Too much pressure let in by the transmission solenoid would induce harsh and aggressive gear changes. Or, and if the transmission fluid pressure is too low, there isn’t enough lubrication or cooling.

As a result, your gearbox would suffer erratic and odd shifting. Not to mention wearing out rapidly, or overheating, and prematurely failing. Your transmission fluid pressure can be altered on the fly thanks to the solenoids. Any signals and data are processed by a microcontroller, before opening and closing a solenoid respectively. Hence, ensuring that you can shift gears smoothly, quietly, and comfortably.

Here’s a step-by-step process of how they work:

1. As you’re driving, your car’s speed and RPMs are measured by a variety of vehicle and engine speed sensors.
2. Data gathered by those sensors are sent to the ECU or TCM to be analyzed. Once extrapolated, it can determine the most appropriate moment to shift or down the gears.
3. Their analysis translates into 12V electric signals, which are sent to the transmission solenoids to have the transmission up- and down-shift accordingly.
4. The solenoids are equipped with a spring-loaded plunger (which opens and closes), which is wrapped with a wire around it.
5. A burst of electrical charge (from those electric signals) through the coil of wire will induce the plunger to open.
6. Therefore, allowing gearbox fluid to circulate into the valve body, and bring pressure to whichever parts of the transmission that’s necessary to make a gear change happen.

What Are The Symptoms That Warrant A Solenoid Replacement?

The transmission solenoids, as we hinted before, come in a pack. There are varying types of solenoids, and they each perform different functions to facilitate controlling the flow of fluids. Usually, you’re able to find the solenoid pack in either the transmission control module or the valve body. The latter’s a maze-like assembly that contains passageways where fluids can travel throughout the transmission.

In short, a failure in this component – thus, requiring a solenoid replacement – will result in poor shifts and bad or erratic performance, besides excessive wear and tear on the gearbox. On the bright side, it can display very clear-cut symptoms whenever they’re just about an inch from death. By paying close attention to it, you may be able to facilitate a solenoid replacement before it’s too late.

Usually, this will come in odd shifting and behavior from the transmission, which you should be able to immediately spot as soon as you start driving…

1. Random And Erratic Shifting Action

As the solenoids begin to fail, hydraulic (transmission) fluid pressure is likely to have been thrown out of whack. Consequently, your gearbox’s many moving parts – clutches, gear sets, brake bands, and so on – are left without sufficient force to actuate. This results in your car’s transmission not working as it should, which is noticeable in the way it drives and changes gears.

Some examples include the transmission skipping or missing gears while shifting up or down. You may also notice the gearbox repeatedly changing back and forth between the same gears. Or, the gearbox might instead leave you stuck within a particular gear, and no matter what you do, it’ll refuse to shift gears. Elsewhere, it might shift aggressively and harshly, at too low or high of an RPM.

2. Inability To Shift Down The Gears (Downshift)

The type of failure suffered by individual transmission solenoids does vary. At times, they won’t open or close at the right time. Alternatively, only some of the solenoids (among the rest of the pack) may not function at all. Another stage or type of failure that the transmission solenoid can go through, is being permanently stuck opened or closed, as the plunger won’t retract or push open.

With a stuck solenoid, this prevents the transmission fluid from being able to flow into the valve body. In effect, causing a drop of pressure, and ensuring that your gearbox can’t shift into the correct gears. You’ll notice that your engine continues to rev upwards, even as you’re slowing down and braking. At other times, the transmission might stick you into neutral, and won’t shift to a different gear.

3. Very Slow And Delayed Shifts

There are very tight tolerances as far as transmission fluid pressure is concerned in making sure that a gearbox can change gears smoothly and progressively. This is especially the case with the automatics that the vast majority of car buyers opt for. If the fluid pressure isn’t regulated and controlled properly by the solenoid, you can expect slow or delayed shifts.

It can leave you hanging within a select gear for far too long and would take ages just to move into a higher or lower gear. Sometimes, you may also feel as though the transmission is stuck somewhere in neutral, and wouldn’t permit you to move forward. This is noted in jerky or lurching gear shifts, as well as poor performance and tardy acceleration from your car.

4. Check Engine Light Or Transmission Light

Given that the solenoids are connected directly to your car’s computers – both the ECU and TCM – any issues that it faces will have been logged. Problems will be noted down as error codes, at which point you’ll see a series of warning lights appear on your dashboard. Most often, these would either be the Check Engine Light (CEL) or the transmission warning light.

Just remember that these warning lights can appear for any number of troubles relating to the engine and transmission. As for CEL, it can prompt issues as simple as the gas filler cap not being tight, or perhaps due to emissions-related faults. The only way for you to be certain as to what’s prompted the CEL to appear in the first place is by plugging in an OBD scanner. We’ll discuss more of that later.

5. Your Car Goes Into ‘Limp Home’ Mode

Following the appearance of warning lights or problems detected by the car, it may prompt it to drive in its ‘limp home’ mode. This is a safety feature built into most vehicles to prevent you from stressing out the already compromised powertrain. It includes issues faced by the engine or transmission, such as in the case of a set of faulty gearbox solenoids.

The limp home mode will limit your vehicle to around 2nd or 3rd gear to limit your vehicle’s speed and usage. It might also prevent you from revving any higher than 2,500 to 3,000RPM, depending on your vehicle. This doesn’t immobilize the car completely, as it still allows you to drive, albeit very slowly. It’s a good opportunity to head down to your local workshop, to have it checked.

What Are The OBD Error Codes For A Solenoid Replacement?

As we mentioned earlier, you can plug an OBD scanner or reader to extract error codes spat at you by the car. These are gathered and saved by the ECU and TCM, which can be immensely helpful in diagnostics and understanding what’s precisely wrong. This can enable you to analyze the error codes logged. Here are the common diagnostic error codes pertaining to a faulty transmission solenoid.

Note, these here are generic error codes, rather than manufacturer-specific ones. This list comes from the folks over at OBD2Pros, where you can learn more about what each diagnostic trouble code (DTC) means. If your error codes don’t match up with these, it should only be a quick Google search away.

Solenoid Replacement Error Codes – Transmission Control:

• P0700 – Transmission Control System Malfunction
• P0701 – Transmission Control System Range/Performance
• P0702 – Transmission Control System Electrical

Solenoid Replacement Error Codes – Fluid Pressure Control:

• P0745 – Pressure Control Solenoid Malfunction
• P0746 – Pressure Control Solenoid Performance Or Stuck Off
• P0747 – Pressure Control Solenoid Stuck On
• P0748 – Pressure Control Solenoid Electrical
• P0749 – Pressure Control Solenoid Intermittent
• P0775 – Pressure Control Solenoid B
• P0776 – Pressure Control Solenoid B Performance Or Stuck off
• P0777 – Pressure Control Solenoid B Stuck On
• P0778 – Pressure Control Solenoid B Electrical
• P0779 – Pressure Control Solenoid B Intermittent
• P0795 – Pressure Control Solenoid C
• P0796 – Pressure Control Solenoid C Performance Or Stuck off
• P0797 – Pressure Control Solenoid C Stuck On
• P0798 – Pressure Control Solenoid C Electrical
• P0799 – Pressure Control Solenoid C Intermittent
• P0960 – Pressure Control Solenoid A Control Circuit / Open
• P0961 – Pressure Control Solenoid A Control Circuit Range/Performance
• P0962 – Pressure Control Solenoid A Control Circuit Low
• P0963 – Pressure Control Solenoid A Control Circuit High
• P0964 – Pressure Control Solenoid B Control Circuit / Open
• P0965 – Pressure Control Solenoid B Control Circuit Range/Performance
• P0966 – Pressure Control Solenoid B Control Circuit Low
• P0967 – Pressure Control Solenoid B Control Circuit High
• P0968 – Pressure Control Solenoid C Control Circuit / Open
• P0969 – Pressure Control Solenoid C Control Circuit Range/Performance
• P0970 – Pressure Control Solenoid C Control Circuit Low
• P0971 – Pressure Control Solenoid C Control Circuit High

Solenoid Replacement Error Codes – Shift Timing:

• P0785 – Shift Timing Solenoid A Malfunction
• P0786 – Shift Timing Solenoid A Range/Performance
• P0787 – Shift Timing Solenoid A low
• P0788 – Shift Timing Solenoid A High
• P0789 – Shift Timing Solenoid A Intermittent

Solenoid Replacement Error Codes – Shift Lock:

• P0928 – Gear Shift Lock Solenoid Circuit / Open
• P0929 – Gear Shift Lock Solenoid Circuit Range/Performance
• P0930 – Gear Shift Lock Solenoid Circuit Low
• P0931 – Gear Shift Lock Solenoid Circuit High

Solenoid Replacement Error Codes – Shift Solenoids:

• P0750 – Shift Solenoid A Malfunction
• P0751 – Shift Solenoid A Performance Or Stuck Off
• P0752 – Shift Solenoid A Stuck On
• P0753 – Shift Solenoid A Electrical
• P0754 – Shift Solenoid A Intermittent
• P0755 – Shift Solenoid B Malfunction
• P0756 – Shift Solenoid B Performance Or Stuck Off
• P0757 – Shift Solenoid B Stuck On
• P0758 – Shift Solenoid B Electrical
• P0759 – Shift Solenoid B Intermittent
• P0760 – Shift Solenoid C Malfunction
• P0761 – Shift Solenoid C Performance Or Stuck Off
• P0762 – Shift Solenoid C Stuck On
• P0763 – Shift Solenoid C Electrical
• P0764 – Shift Solenoid C Intermittent
• P0765 – Shift Solenoid D Malfunction
• P0766 – Shift Solenoid D Performance Or Stuck Off
• P0767 – Shift Solenoid D Stuck On
• P0768 – Shift Solenoid D Electrical
• P0769 – Shift Solenoid D Intermittent
• P0770 – Shift Solenoid E Malfunction
• P0771 – Shift Solenoid E Performance Or Stuck Off
• P0772 – Shift Solenoid E Stuck On
• P0773 – Shift Solenoid E Electrical
• P0774 – Shift Solenoid E Intermittent
• P0972 – Shift Solenoid A Control Circuit Range/Performance
• P0973 – Shift Solenoid A Control Circuit Low
• P0974 – Shift Solenoid A Control Circuit High
• P0975 – Shift Solenoid B Control Circuit Range/Performance
• P0976 – Shift Solenoid B Control Circuit Low
• P0977 – Shift Solenoid B Control Circuit High
• P0978 – Shift Solenoid C Control Circuit Range/Performance
• P0979 – Shift Solenoid C Control Circuit Low
• P0980 – Shift Solenoid C Control Circuit High
• P0981 – Shift Solenoid D Control Circuit Range/Performance
• P0982 – Shift Solenoid D Control Circuit Low
• P0983 – Shift Solenoid D Control Circuit High
• P0984 – Shift Solenoid E Control Circuit Range/Performance
• P0985 – Shift Solenoid E Control Circuit Low
• P0986 – Shift Solenoid E Control Circuit High
• P0997 – Shift Solenoid F Control Circuit Range/Performance
• P0998 – Shift Solenoid F Control Circuit Low
• P0999 – Shift Solenoid F Control Circuit High

How Much Does A Solenoid Replacement Cost?

Now, we come to the tricky question of how much does a transmission solenoid replacement cost? It’s a vital component of any automatic gearbox’s functionality, performance, and reliability, despite its tiny size. The good news here is that a solenoid replacement is among the more affordable repairs for transmission-related issues. That’s relatively speaking, of course, and the final tally does vary.

It’ll depend a lot on the make and model of the car you’re driving, and the gearbox it uses. More complex and high-tech transmissions may require more time and effort to replace the solenoids buried within. In short, that’ll lead to ever-increasing solenoid replacement costs. In general, however, you can likely expect a total bill of around $150 to $400, on average. This accounts for labor and parts, as well.

https://www.youtube.com/watch?v=02IDgs7GKZk

To break it down further, the task of replacing a transmission solenoid at the local mechanic will take around 2 to 4 hours. Typically, a workshop would charge an hourly labor rate between $60 to $120. This far outweighs the price of the solenoid itself, which can be bought for as little as $15. Or, around $100 for the higher-end solenoids. Do bear in mind that the costs mentioned here are for a single unit.

If several of your solenoids fail at once and need replacement, you’ll have to add a bit more to the bill, especially for the parts. A pack of solenoids can be bought for approximately $50 to $300. Now, you’ll have to include slightly longer working hours for the mechanic to replace several solenoids instead of just one. In total, you’ll end up with a solenoid replacement cost of around $250 to $600 for a pack.

Solenoid Replacement Cost, And Why Are They Expensive?

Additionally, you’ll need to factor in more complicated transmissions to work on. Therefore, you could also see the final bill for a solenoid replacement skyrocket to $700+. Even closer to $1,000 with luxury, heavy-duty, or high-performance vehicles. Several factors ultimately influence the lofty expense for solenoid replacements:

• Location – With some cars, the solenoids can be removed and replaced without having to remove the valve body. Others, however, require extensive disassembly of the valve body to get at the solenoids. Moreover, doing so in most cars first asks you to remove the entire transmission assembly from your car, hence why it can be quite costly. Again, that’ll depend on the vehicle in question.
• Pack – In certain vehicles, you can get away with replacing just a single faulty solenoid, and the rest can be left as-is. Nonetheless, some cars demand that you replace the entire solenoid pack, even if just one of them fails. On top of that, some vehicles have the solenoids integrated with the valve body. As such, you’ll have to replace the entire valve body, which costs more than $1,000.
• Other Parts – As you’re replacing the transmission solenoids, it’s always recommended that you’d also consider replacing other parts in there, too. Commonly, these would include flushing and changing the transmission fluid, as well as getting a new filter. The condition of the fluid is important, mind you. Dirty or contaminated transmission fluid can prematurely wear out or break the new solenoids.

Solenoid Replacement Cost Samples:

• Ford F-Series – Parts: $380-$420/ Labor: $200-$220/ Total: $580-$640
• Chevrolet Silverado – Parts: $400-$430/ Labor: $240-$270/Total: $640-$700
• Ford Focus – Parts: $380-$420/ Labor: $200-$220/ Total: $580-$640
• Ford Fusion – Parts: $380-$420/ Labor: $200-$220/ Total: $580-$640
• Toyota Camry – Parts: $400-$430/ Labor: $210-$260/ Total: $610-$690
• Toyota Corolla – Parts: $400-$430/ Labor: $210-$260/ Total: $610-$690
• Honda CR-V – Parts: $400-$430/ Labor: $210-$260/ Total: $610-$690
• Honda Civic – Parts: $400-$430/ Labor: $210-$260/ Total: $610-$690
• Nissan Altima – Parts: $350-$400/ Labor: $190-$210/ Total: $540-$610
• Honda Accord – Parts: $400-$430/ Labor: $210-$260/ Total: $610-$690

How To Prevent Needing A Solenoid Replacement?

So far, we can conclude that the small size of a transmission solenoid doesn’t translate directly into it being a simple item to replace. Owing to the need to disassemble parts or much of the gearbox before we could even get to the solenoid, this means that a solenoid replacement cost is no trivial matter. As such, it would be best if we could avoid needing to replace the solenoid in the first place.

The bad news here is that transmission solenoids can’t last forever. If you regularly use your car, most expect a lifespan of around 1 to 3 years for the transmission solenoid. Although, this estimate is being rather pessimistic. Realistically, it’s hard to approximate when the solenoid is bound to fail. Thus, why paying close attention to the symptoms that we detailed earlier is a handy sign to get it fixed.

Any transmission solenoid will inevitably undergo immense wear and tear over time. It’s only a case of doing your best to care for it, which can aid in extending its lifespan. The most obvious way to maintain the longevity of your solenoid – and the rest of the transmission – is by regularly changing the transmission fluid. As they age, gearbox oil will get dirty, as gunk and sludge begins to build up.

Letting this old transmission fluid circulate in your gearbox can be damaging to the solenoid. It’s able to cause issues, such as debris, dirt, and gunk floating in the fluid jamming the solenoids. It could result in the plungers sticking or failing to open and close properly. On top of that, viscous, sludgy fluids are harder to circulate, forcing the solenoids to work harder to pressurize it, thus wearing them down.

Solenoid Replacement Prevention Tips:

Besides changing out the transmission fluid regularly, here are a few more prevention tips…

• Service Your Transmission – The gearbox has an abundance of components that need to be serviced at select intervals. The most common one is the transmission fluid filter. That’s in addition to the fluid itself, as we explained earlier. A fluid flush is also a good idea to forcefully remove any contaminants or sediment in the system.
• Synthetic Fluid – You may also consider replacing your car’s conventional transmission fluid with a synthetic mixture. Heat is a key player in breaking down transmission fluid, leaving them burnt out or worn. As a result, they’re unable to perform just as well in regards to lubrication and cooling. It’s not an issue with synthetic transmission fluids, which are more resistant to heat.
• Secondary Cooler – Transmissions are destroyed mainly due to excessive heat. It can damage seals, as well as valves, solenoids, electrics, and many other components. If you typically drive around in hotter climates, it may prove useful to invest in a secondary, auxiliary transmission cooler. This could have a significant impact on reducing the operating temperature of your gearbox.
• Drive Modestly – Another great way to prevent your transmission from being scrapped is practicing a more moderate driving style. Aggressive driving will not only put more strain on the engine but also the transmission. So, be more gentle with the throttle pedal, and allow your car to shift gears more gradually, instead of forcing it to redline at all times.

Transmission Solenoids: Facts You Need to Know

1. Modern automatic transmissions use pressurized hydraulic fluid to change gears.
2. The car’s computer activates a transmission solenoid to direct transmission fluid into the valve body to engage the correct gear.
3. The Engine Control Unit (ECU) or the Transmission Control Unit (TCM) sends a signal to a shift solenoid to execute an upshift or downshift based on data from speed sensors and engine sensors.
4. A solenoid can control a single gear or multiple gears, depending on the complexity of the design.
5. A failed transmission solenoid can cause erratic shifting, transmission won’t downshift, or severe shifting delay/stuck in neutral.
6. The ECU registers an error code and triggers the check engine light if something goes wrong with the solenoid.
7. A scan tool can determine the source of the solenoid’s problem, which could be a bad ground or a failed solenoid pack.
8. Labor cost for replacing a shift solenoid ranges from $120 to $400, and the total cost can range from $250 to $600, depending on the make and model of the vehicle.
9. Solenoids are located inside of the oil pan and can be replaced individually or as a pack.
10. Regularly changing the transmission fluid at the factory-recommended intervals can extend the life of transmission shift solenoids.

Final Thoughts

This should be a great place to sign off on our guide on solenoid replacement. While these individual solenoids are fairly tiny, they are consequential for your transmission’s operation. Faulty solenoids are easily capable of compromising your driving experience and vehicle performance. Not to mention, the additional stress that you’re putting on the gearbox, which could ultimately damage the entire thing.

Seeing how intertwined they are, solenoids aren’t exactly cheap to replace. It often requires removing much of the gearbox to even access it. Still, it’s well worth paying given that a brand new transmission would set you back thousands of dollars. Maintaining the solenoids is much easier, by comparison. All it takes is diligence on your behalf to make sure the transmission fluids are regularly changed.