What Does Resetting the PCM Do?

The powertrain control module (PCM) controls your ride’s powertrain. It manages your engine, transmission, and other related components based on the data sent by various sensors. In a nutshell, the PCM is the brain of your vehicle.

Resetting the PCM will not  typically clear all learned parameters and adaptive data in all vehicles. You’ll have to manually do it using a san tool. You can also disconnect both battery cables. Hold them together for about five minutes to discharge any residual voltage before reconnecting them.

So when should you reset the PCM? Learn more about the intricacies of resetting the PCM.

Reasons to Reset Your PCM

Returning your vehicle’s computer to its factory setting might be the right choice in the following circumstances.

You Want to Clear a Fault Code

Some drivers reset their vehicle’s PCM to clear fault codes or resolve an illuminated check engine light. However, it’s important to note that doing so doesn’t always fix the issue.

In some cases, resetting the PCM won’t deactivate the check engine light; only addressing the problem will do. The warning light usually resets itself after at least ten successful cycles. A single cycle involves starting the vehicle cold, driving until it’s warm, and turning off the engine after the trip. Note, however, that this depends on the actual trouble code that’s logged.

You can reset the PCM immediately after fixing the code to confirm if you’ve really fixed the issue. If you weren’t successful, the PCM will trigger the check engine light again.

It’s Recommended After Component Replacement

A PCM reset might be necessary when you replace certain vehicle components to let the computer relearn and adapt to the new part. For example, some experts recommend resetting the PCM after changing the oxygen sensors.

You Want to Solve Starting Issues

On some models, resetting the PCM could solve hard starting issues. However, it’s seldom a permanent fix, especially when there’s an underlying problem behind the starting problems. The best thing to do is to let a mechanic diagnose the issue.

You Recently Replaced Your Car’s Battery

The PCM usually resets itself when you replace your malfunctioning or dead car battery. However, there can be instances when the PCM doesn’t automatically adjust to the new battery, which could trigger the check engine light. You can opt to reset the PCM if this happens.

Is It Safe to Reset My Car’s PCM?

Yes, resetting your car’s computer is completely safe. Performing a PCM reset will only put your car back to its factory settings, so it shouldn’t cause any component to develop problems.

However, note that the PCM will have to re-learn your driving style and habits after a reset, which could affect engine performance. So it’s recommended to reset your PCM only when it’s needed. If you’re unsure about resetting the PCM, you can consult a trusted mechanic.

How to Reset PCM

There are two common ways to reset the PCM: disconnecting the car battery and pulling the fuse from the fuse box. Note that there might be other ways depending on the vehicle’s year, make, and model. Let’s look at the typical methods in detail:

Method #1: Disconnect Car Battery

The exact steps for this method depend on the vehicle, but here’s how it’s typically done:

1. Open the hood and look for the car battery.
2. Remove the negative battery cable.
3. Wait for around five minutes.
4. Turn the headlights on with the battery disconnected to empty the power in the capacitors.
5. Put the terminal back on again.

Method #2: Pull the Fuse

The tricky part of this method lies in locating the fuse box. You can consult your manual to determine its exact location. Then, you can reset the PCM by pulling the fuse, which typically involves these steps.

1. Find the fuse for your PCM. If you’re unsure of which fuse to remove, consult the fuse box diagram in the owner’s manual or consult online resources.
2. Remove the fuse from the box.
3. Put it back on after 10 to 20 seconds.

Remember that these steps are only meant to guide you in the process. If you’re not a seasoned DIYer, we recommend taking your car to an auto repair shop. A mechanic can easily do a PCM checkup and reset for you.

How Will I Know Whether the PCM Reset Was Successful?

If you reset the PCM to clear a check engine light, then you’ll know that it’s successful when the light stays off after restarting your car. However, the check engine light could illuminate again even after a successful reset if the problem it’s indicating remains unresolved.

The easiest way to know if the reset is successful is to check if the radio stations you saved before are still there. If it’s not, you did reset your PCM correctly.

Does Resetting the PCM Affect Emission Testing Readiness Monitors?

In some states, emission testing is mandatory. This test involves connecting to your car’s PCM to check your readiness monitors. Readiness monitors basically observe the performance of your car’s emission related systems.

If you recently cleared trouble codes or disconnected your car battery, the monitors will also be reset. Once this happens, you’ll need to follow a specific driving pattern to enable the monitors to initialize again.

How Does the PCM Work?

The PCM receives data in the form of signals from various vehicle sensors. It makes critical decisions to keep the engine at its optimal performance using the information.

For example, it decides when to inject fuel, how much fuel to inject, and when to fire the spark plugs. You can check out this comprehensive guide to learn more about the PCM.

Why Is the PCM Important?

The PCM controls a lot of things in your vehicle. If it’s faulty, it could disrupt communications with other onboard control modules, resulting in problems that can make driving difficult or dangerous.

Like any other computer system, the PCM can develop issues. Resetting it can sometimes resolve them, but it shouldn’t be your go-to solution for all problems. It’s best to pinpoint and address the issue to prevent problems down the line. Take a trip to an auto repair shop when you suspect something is wrong with your ride.