I have a 2005 Saturn Ion that is my daily driver. My commute to work is 45 min all highway. At @35mpg it earns it's keep over my gas guzzling GMC Sierra. Car has been pretty dependable. I have only had to do a complete tune-up on it when it started running rough and I had to replace the plastic windshield wiper armature when it failed. Like I said over-all good car. Book value is not much so I do not want to put a lot into it but these days used cars are getting expensive as well to replace.

My most recent problem is crazy. It started out as what I thought a fuel pump problem. While driving down the road the RPM's and speed would suddenly drop. Now it has developed into once the car warms up the automatic door locks start clicking and then RPM's climb quickly like it missed a gear and the speedometer drops to 0mph while it's coasting at a high speed. The digital odometer readout will say POWER STR. After a few seconds everything will correct itself and be fine for a few miles and it will start all over. I am getting the following codes: P0420, P0700, u101, P0717, P1810 P0722 and P0741 (which are all transmission related). I took it to my local transmission shop and they said it is having an electrical issue with communication between the ECM and rest of the car. They said ECM loses power and keeps trying to relearn car. Advised I take it to local shop that specializes in electrical issues. Everything I have seen on line is pointing to the TCM, possibly a grounding issue. I hate to just throw parts at it but I'm thinking about just replacing the TCM and see if that is it. Some folks have advised it might just be a bad battery, transmission fluid level, or even the catalytic converter is clogged up. Unable to easily check transmission fluid level without a dipstick. Anyone else have this issue and know a remedy? I will put the codes below with explanation too.


P0420 - Catalyst system efficiency below threshold bank 1
P0700 - Transmission control system (mil request)
u101 - Lost communication with TCM
P0717 - Input turbine shaft speed sensor A circuit no signal
P1810 - TFP valve position switch circuit
P0722 - Output shaft speed sensor circuit no signal
P0741 - Torque converter clutch circuit performance/stuck off