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Problems/Service/RepairsIf you have a problem with your HHR, want a tip on repairing or performing a particular service to you HHR here is the place to post!
Did they tell you that P0742 means TCC stuck on? Which means the TCC solenoid is sticking.
P0842 means the TFP means that it is trying to turn the TCC off but the TCC is shorted to ground i.e.: coils fried.
P0138 means the #2 O2 sensor is reading high. Any chance you installed a Bosch #2 O2 sensor?
Did you know that any big box auto parts store will read codes for free? Why go to a dealership if it does not involve a warranty or recall? They have the same access to information as I do but don't necessarily have the intelligence or time to understand. The ASE certificates on the wall are purchased.
Has there been any under hood activity just before this; like disconnecting the transmission electrical connection, ATF change, any electrical work? Could be the 20-way connector is loose/dislodged/poorly reconnected. Any internal wiring is pretty much stationary, maybe a gremlin snuck into the trans cover.
If not the TCC solenoid valve is bad.
You need a new NTK/NGK #2 O2 sensor.
The only thing a wiring schematic will tell you is the color of the wires in the 20-way connector.
Donbrew
Thanks for the feedback and diagrams.
Now for the Paul Harvey:
I bought the 2011 HHR used from an person who advertised on "Marketplace" It had 149K miles on the odometer. No CEL or other alerts displayed. I took it for a test drive around town and everything worked fine except for the radio, only one speaker was working and the passenger side window wouldn't operate by using the driver side control, The car was very clean under the hood and the underneath was clean and dry. The Carfax was clean without any red flags, the car was maintained regularly I could see it had replacement struts and suspension .
Soon after the purchased it became apparent that the transmission had some issues. The transmission works normally when cold but after several miles of normal driving ( maybe 10 -15) the torque converter clutch engages and won't disengage until the car almost comes to a complete stop. This caused very hard shifts and for the engine to shudder just before coming to a stop, sometimes the engine will stall when coming to a stop.
I was thinking that the Amoco tech might be on the right track with the leaking torque converter seal which might work normal with cold oil but leak enough when hot to cause the problem. I wasn't sure enough so I took it to the dealer for a second opinion.
The dealers report stated, " P0742 Torque Converter clutch system stuck on current" and "P0842 - Transmission fluid pressor switch low voltage" for the TCM
"P0700- transmission, P0xxx EVAP Small leak" and "P0138 Oxygen sensor high voltage sensor #2" for the ECM
"153661 scanned tcm for codes P0742 P0842 diag leads to internal solenoid failure will need to go internal for further diag 1997997"
Even with all these codes the CEL will come on once in awhile and then go out without taking any corrective action, I was thinking that the CEL was only responding to the small Evap leak.
I didn't really want to get into a major transmission repair and associated cost so I was thinking if I could figure out how the torque convertor clutch works I could cut the wire leading from the TCM and add a manual switch to control when the TCC would be engaged or not.
I don't know if this is possible. I don't know if the TCC uses hydraulic pressure to engage or disengage it.
Looking at the diagrams you provided I could try cutting the wire that goes to pin T and see what happens. If the TCC doesn't engage after cutting this wire I could try adding a single pole toggle switch to see if I could control the TCC manually. If the TCC is engaged by spring pressure and disengaged by hydraulic pressure this quick fix might not work.
The P0742 TCC solenoid is causing the P0842., not the other way. The O2 sensor and air leak are un related.
It is possible to replace the solenoids without pulling the engine and trans. I think there is a how-to in the how-to section of this forum, and probably on youtube. AAMCO will certainly claim that you need a new trans, that is what they sell.
Labor for replacing the TCC solenoid is listed at 6.3 hours, I am guessing the part is around $30.
If a seal was leaking there would be puddles under the car and much bigger trouble.
What is the EVAP leak code number? P0442? Probably need to look at the gas cap.
P0700 just means there is a transmission code i.e. the P0742 & P0842.
If you know the sellers screen name you could search the forum for his posts, maybe get some history
Thanks DonbrewThe evap leak code could be p0442? It's a poorly hand written note on a copy of the service tech report.
I'll do some YouTube searches for a related video clip on repairs
Thanks again
This thread is great and timely. My 08 AA5 has been sitting for almost 2 years with trans issue. Mine is a super high 1-2 shift point and harsh engagement from N or P to D. My research shows solenoids or maybe a chewed harness. I need to get this running for my soon to be driving youngest son...or maybe give him my Equinox and get back in the HHR. Thanks everyone.
11-06-2022, 12:32 AM
