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Hardshifting All Gears/no TC/CEL

3K views 7 replies 3 participants last post by  Coby7 
#1 ·
I have a 2006 Cobalt LT coupe 2.2 at 130K miles. Ran great since I bought it around 124K miles.

A little background of what I've done since what I'm going to explain started:

Replaced both up and downstream O2 sensors as they were bad, and changed out the exhaust (catback) since it was heavily corroded it out.

Drove the car for 2 days no issues, until I was meeting a friend for lunch got to a red light and the NO traction control light came on. Didn't care much about it yet until I started driving and EVERY single gear was a really hard shift like jolting me forward. I met my friend which was just 2 miles down the road and when I finally had left, saw the CEL light was on.

I have an OBDII reader and here are the codes I'm pulling:

P0030 heater control circuit 1 bank 1 sensor 1
P0036 as above bank 1 sensor 2
P0102 MAF circuit low
P0135 02 sensor heater circuit bank 1 sensor 1
P0141 as above bank 1 sensor 2
P0443 evap emission system purge control valve circuit

My questions mainly are: 1. What caused brand new 02 sensors to go bad again so soon? 2. Would ANY of these issues cause the transmission to be jerking like it is? 3. Is there anything else I should check since these are vital systems that could have caused any other problems (best to address now then later)?

I've had several home mechanics from which one is certified and used to work for Ford (yeah its Ford but whatever) and he recommended the fluid being changed in the tranny. I have had others say it could be the wheel speed sensor, but why does it not show up as a code?

Since that day, the car has sat parked, I start it up from time to time, but I have someone coming this weekend to help me fix it up; before I buy any parts what is everyone's best advice?

No rude comments, or misleading information please. I'm turning to people on this forum who know more than me for help. Please send me in the right direction. Thanks!
 
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#2 ·
First of all for both HO² sensors to fail at the same time is highly improbable. I suggest you clear the codes and take your Cobalt for a short ride until the cell comes back on since those might be history codes from a previous CEL. Re-read the codes if the cell comes back on. The more likely cause for your lost of GMLan communication between TCM/PCM is one of 2 possibilities. 1. The TCM/PCM fuse on the BCM fuse block is corroded or pitted or 2. You lost communication due to corrosion on some pins of either P1 or P2, so remove these and re-insert a few times, if this cures the problem for a little while next time clean them with contact cleaner and add a bit of dielectric grease.
 
#3 ·
I will try your recommendation. My scanner reads no voltage on both o2 sensors, so I'm not exactly sure with those. I didn't think it was probable either. Either way, thanks for your help. I will post if it worked so others can follow your advice. Thanks again!
 
#4 · (Edited)
Maybe you lost the voltage going to the sensors, did you check the underhood fuse block for Exhaust fuse. You may have a frayed wire touching ground. This voltage supplies both HO² sensors and the rear EVAP canister and may also supply the MAF sensor. But not sure this would explain your hard shifting. Did you also lose your fuel gauge indication?

 
#5 ·
Didn't even think of checking the fuse, good call! I will do this for sure; as for the fuel gauge indication I still have it. The car when it does run, is full rich burning fuel up like crazy.

Just ran it yesterday, didn't drive it anywhere just let it idle and it sounds like it wants to die at this point. Very hesitant when I just did a tap on the accelerator to bring up some RPM's, and the whole lighting system dims when I do that, not sure why everything would dim either. Never did this before.

Anyways, I'll do what you said in your earlier post, and this one about the fuse, I've had someone mention the fuse before but didn't think anything of it because there was no explanation on what the fuse covered until you explained it more so thanks for the knowledge! I'll keep you posted on what happens from there.
 
#6 ·
Dirty or loose/disconnected grounds? Maybe someone did a mod and forgot a grounding wire. One single bad/corroded ground could cause a slew of problems, all at once...clean the ground and every CEL disappears (hopefully). Looking at the ground distribution electronics schematics would help.

Some GM cars concentrate all grounds in a single place, but I think my '07 cobalt has over a dozen different grounds when I last looked at the schematics.
 
#7 ·
update

Followed coby7's advice. Found out that the 10amp fuse was in fact dead, and replaced it. Disconnected the battery and reconnected. Engine started right up no hesitation or nothing. CEL and NO traction control light was on anymore.

I know disconnecting the battery resets everything. Connected the scanner to the car, O2 sensors are reading again. Transmission was shifting normal again, no issues.

Until... not even a mile and half around the block, NO traction control light comes back on and IMMEDIATELY the transmission goes back to hard shifting again. At least the engine runs good, and Thanks coby7 for fixing half the problem haha appreciate it!

Now to solve the transmission issue, thinking it has to be a wheel speed sensor or something. If I can't figure this out soon, I'm just gonna take the car to a shop and get ripped off, better than guessing and spending money on parts that probably don't need to be replaced; after all the car's just been sitting for months as I have another vehicle and the cobalt was just for commuting purposes.

Any other suggestions or advice?

---------- Post added at 06:59 PM ---------- Previous post was at 06:57 PM ----------

before all this happened, the last thing was done was a catback exhaust installed to replace the old corroded one. A muffler shop did this and next day had the problems, is there any grounds near their area of work under the car where this could have happened? I'm trying to backtrack to the last known day where there was any problem and it keeps coming back to the shop. I'm not sure if maybe they hit something by accident or purposely did it... Who knows, it was a while ago, and I'm still trying to clean up the mess.
 
#8 ·
The way you describe the last time the problem came up suggest that you have a bad wheel bearing speed sensor.
 
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