By December 31, 2012 0 Comments Read More →

Engine Code P0601 – P0606 PCM Failure?

Reader Question


I have a Malibu Maxx, 3.5 L engine with AC, 148,000 miles, VIN:1G1ZT62895F298419. I have had DTC codes P0601, P0606, U0107 check engine, along with T/C light display kick on three times.

Once on one occasion (Thanksgiving); twice on a second driving occasion (Dec: Home for Christmas). This has occurred during long distance driving (800 miles).

Last time the engine also cut off. I have recorded then cleared the codes each time and continued traveling. The codes, in the three instances that this has happened, occurred at 70-75 mph speed.

When I reach my destination and am driving around at usual city speeds, I have not experienced the Check Engine light coming on. It seems, so far, that if I am below 70 mph (say 65 mph), I do not encounter this condition…at least not yet.

From the codes, I believe it is the PCM/ECM module. I look the codes up and know what they designate. Of course, it could be other items. After I clear codes and continue driving, the engine seems to run fine. In the last code instance, I was not using speed control which was engaged in previous instances.

I have been to a Chevy dealership, and although I provide the codes, they instruct me to run the car until the Check Engine light comes on, then they can put it on their diagnostic machine (at a cost) to diagnose problem.

Question: I have asked Chevy dealer if their machine goes deeper than my hand held code reader without an adequate reply. I can provide the codes. Running the car until the Check Engine light comes on and the engine cuts off during a long distance drive may strand me somewhere (thanks for the advice Chevy).

Car Chronological History:

Car battery about 1 year in on a 3 year battery.

Feb 2012: Fuel pump changed. Fuel system cleaned (3-stage system) by Firestone.

Since the above, I have had check engine light come on in city driving. Codes: P0455, P0461, P0442 relating to emissions leak. I was advised to get a new Chevy gas cap and twist the cap on 5 or 6 times to assure a good seal. I haven’t seen these codes since I now do this, although I think it came on one time since. I just clear the code, twist the cap.

Prior to second driving occasion, I changed wires and spark plugs, cleaned Mass Air Flow Sensor, cleaned throttle body, renewed air filter. This was performed by myself under the direction of a mechanic (at an Army/Naval Base auto repair facility).

From my research on the internet, I understand this problem to be a faulty PCM although there is a slight possibility of another factor causing it such as voltage control issues.

1) disconnect battery cables for 10 minutes (both positive and negative) to wipe out everything. I have also been told to touch the positive and negative cables together (after disconnect) to bleed out any residual charges.

2) One trouble shooting chart recommends a first course of action would be to flash reprogram the PCM to determine if that is a fix prior to a PCM replacement or would another course of action be pursued.

3) If U0107 code is suspected to cause the other faults to cascade in, can the throttle body be hooked up to a diagnostic machine to check out electronics and operation?

4) For cost savings, a used PCM may be located for my VIN, programmed and installed by an electrical automotive shop (programming is done by Chevy). Is this prudent for cost savings.

I travel long distances and would not wish this to strand myself if possible. Local dealer said to leave check engine light on, do not clear codes…but then my driving (should I be able to continue) would be inhibited if or until I am able to be at a repair dealership.


Thanks for your question Darrel.

I am not familiar with this particular issue, but have done some research online to see what others have been saying and doing.

I think I would have to concur with them, and you, that this could be a PCM issue, although PCM failure is very rare (at least in my shop) but I think it would be something I would replace in this situation.
I don’t think I would replace it with a used one though, just encase there is an inherent issue with them and you get another one with a similar or same issue.  I would buy a dealer one, or see if you can save some money and buy a re-manufactured one from your local auto parts store.
You will need the dealer to flash it for you, so not sure how much money you are really going to save avoiding the dealer in this case.
I did read lots of threads about the PCM might be under a warranty program. Like a catalytic converter that has a special warranty time period, the PCM just might as well.
Sorry I cant be more help to you, please keep me posted as to what the fix was so I can post to the site and help the next guy.
Have a great New Year


Austin Davis
Posted in: Check Engine Lights

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Austin Davis, consumer car repair advocate. "Hi there! I love to help people solve their car repair problems and I hope my site was helpful to you today. Thank you for stopping by."