I have a 2002 Chrysler PT Cruiser manual transmission with 91,420 miles. The engine service light came on over a month ago (today Aug. 24, 2012). Little by little, a major tune up, a new battery, new plugs, O2 censors, condenser, wires, PVC valve, new gas cap, gas treatment, two tanks of premium gas, the light would not cut off. So off to the Auto Zone to get analyzed twice the code was P0601. Researching the internet, this P0601 code meant the PCM needed to be reprogrammed by the dealer. I called a Chrysler dealer here in Austin and was told that reprogramming the PCM may or may not cut the light off. So today and $100.00 later, the PCM was reprogrammed and the light was off when I left the dealership this morning. But it turned back on when I was leaving work this afternoon. Now what??? My car needs the annual state inspection and it will not pass.
About a block away from the testing station, pull over, remove your negative battery cable for 30 seconds, re-connect and go get it tested while the light is off…This may or may not work, they may tell you the car is not ready to be tested, but it’s worth a try before you start shoveling money into a car that runs fine…Because the next step is a new PCM…That’s a lot of money to satisfy the Emissions Gods…
P0601 “PCM internal controller failure” or sometimes shown as “internal checksum error”.
I’m not aware of any software updates that will fix this, the PCM will have to be replaced.
@Caddyman … your method may not work to fool the emissions folks. At least in Calif I don’t think it would work. The car computers these days-- after an PCM reset – require the car be driven a certain number of miles, through a certain rate of speeds, different gears, cold, and warm, etc. Each car is different. But until the car has gone through all those driving modes, the PCM remains in a sort of pre-closed-loop mode, and when the emissions technicians read the PCM state prior to their testing, the PCM tattle-tells on the driver, saying the car PCM has not reached closed-loop-mode, and has recently been reset (usually by the owner disconnecting the battery). The emissions shop will tell the owner the emissions testing must be delayed until the driver has driven the car through all the modes and the PCM regains closed-loop-mode.
I concur w/@nevada_545 … the PCM probably needs to be replaced.
Thanks Guys for your comments. I have been told a few times by different mechanics that I needed to drive the car about 60 to 100 miles, which I have done. Oh, well.
If the vehicle is running okay, I would try for an emissions waiver before I forked over $1000 to (maybe) repair a problem that causes no problems…
Like others have stated, depending on what state you live in, there most likely has to be a certain amout of monitors set in the ECU before the IM testing is allowed to proceed. Clearing the memory also clears any monitors that were set previous to the memory clearing. There are proceedures in the driving routine you can do in order to speed up the process to set the monitors again. The shop may have them.
If you need another ECU I suggest you try to find a used one. Ebay may be a good place to get one at a good price. You can also purchase repaired units for about half the cost of a new one that will have a warranty.
So since you took it to the dealer and they scanned you and with no issues reset the code. I would go straight to the inspection with the bill from the dealer and tell the inspector “i took it to the dealer and they saw no problems”. They scanned for issues and found nothing to fix.