How to Fix P0606 Code: A Guide to Fixing the PCM Processor Fault

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Obd scanner with code p0606 on the screen

If you are driving and suddenly your "Check Engine" light comes on, it can be scary. What does that light mean? Is my car broken? The answer to both questions is unsure until you determine the problem.

One common issue that people experience is the P0606 code. This blog post will discuss what that code means, the causes, and tips for troubleshooting the issue. Stay calm and read on!

What is Code P0606?

The Powertrain Control Module (PCM), often called the Engine Control Module (ECM), is the computer that controls all of a car's engine functions. The PCM is in charge of monitoring everything related to the vehicle's engine and electrical system.

When the car starts, the PCM runs a self-check to verify all engine components are in working order. If the P0606 diagnostic trouble code is stored due to this self-check, it indicates a processor fault in the PCM.

Symptoms of Code P0606

The occurrence of the P0606 code has multiple symptoms that you can experience in your car. The most common are:

  • Check engine light is on
  • Engine cranks
  • Anti-lock Brake System illuminates
  • Problem in ignition
  • Engine misfiring 
  • Increased fuel consumption

Causes of Code P0606

There can be several reasons why the code P0606 appears in your car. Some of these causes can include:

  • Damaged and corroded circuit wires
  • Faulty or malfunctioned connectors
  • Defective ground circuit wiring
  • A problem in Control Area Network (CAN)
  • Computer glitch (software problem) causing failure in PCM's firewall

How to Diagnose Error Code P0606?

If you experience any symptoms above, you might need a thorough diagnostic for your faulty PCM. You can do several things to fix code P0606; you may follow the steps below.

  • The first step is to retrieve freeze frame data using an OBD-II scanner. Scanning for other codes will provide information on when the PCM set the code and what likely caused the code to be stored.
  • Next, check the PCM for any problems. Visually inspect the wiring and connections that connect to the PCM for fractures, frayed wires, and rusted connectors.
  • After replacing or repairing damaged wires or connections, retests the system. The PCM is likely to need to be replaced and reprogrammed.

How to Fix Code P0606?

After diagnosing this code, you may now be ready to fix it as you have already found out what's causing this issue. Are you mechanically inclined? If so, you can follow the steps below:

Step-by-Step Guide to Replacing PCM Wires

  • Start by disconnecting the battery cables from the PCM (powertrain control module) and wait five minutes for the capacitors to discharge.
  • Remove the PCM cover screws and remove the cover.
  • Next, remove the connector screws and release the connectors.
  • Remove the old wires and replace them with new ones following the same route.
  • Reattach the connectors and screw them in place, then reattach the cover and screws.
  • Reconnect the battery cables (positive first), turn on the ignition, and check for codes.

If the P0606 code is still present, the PCM may have problems. In that case, you might need to replace or reprogram the PCM.

Common Mistakes When Diagnosing the Code P0606

When diagnosing a car issue, it's essential to be as accurate as possible. However, there are times when even the most experienced car mechanic makes a mistake. These are some common mistakes that are often made when diagnosing the code P0606:

  • Not analyzing the root of the problem properly
  • Assuming that the PCM is bad without doing further testing
  • Assuming that a wiring issue is causing the code P0606 without verifying it first
  • Not checking for other codes that may be related to the code P0606

Those are just a few mistakes that can be made when diagnosing the code P0606. If you take your time and double-check your work, you should be able to avoid these mistakes.

Code P0606 FAQs

1. Is this error code serious?

Yes, the trouble code P0606 is severe because it indicates a problem with the PCM. Since the PCM is the brain of the vehicle’s engine management system, it will be unsafe to drive around if there is a problem with it.

2. Is it safe to drive with the P0606 code?

No, it is not safe to drive with the P0606 code. You should get the problem fixed as soon as possible. Any issue related to the PCM should be taken seriously and resolved immediately.

3. Is there anything I can do to prevent this code from showing again?

You should ensure that all your car's systems are in good working order and that no other underlying issues are causing this trouble code. You should always get your car well-maintained and keep a close eye on the engine. If you are not comfortable doing this yourself, take it to a mechanic and have them do regular check-ups.

4. What tools can I use when diagnosing and repairing this trouble code?

You can also use an OBDII scanner to read any trouble codes that might be present and then use that information to help troubleshoot the issue.

5. Can I fail the emission test with the P0606 code?

If your car is not running correctly, it will fail the emission test. P0606 is just one of many codes that can cause your vehicle to fail the emissions test.


If you're experiencing the P0606 code, it's essential to take care of it right away. The PCM is responsible for various engine functions, so leaving this code unchecked can lead to more significant problems down the road.

We hope our instructions have helped you fix the problem and get your car back on the road. If you have any further questions, feel free to reach out and leave your comment below. Thanks for reading!