Greetings,

I'm helping a friend with a HHR recently purchased form a certain national used car chain. She was having hard shifts between 1st and 2nd and maybe into 1st when shifting into drive. Need to check the transmission oil level but forums seemed to indicate that hard shifting behavior can be caused by various faulty sensors.

So no check engine light but I check codes. I get P0102 and P0113. Ok, time to start with the MAF and see if maybe it isn't plugged in right? So I go under there and it isn't plugged in *at all*. Dug around but can't find the cable to even plug it in.

At this point I'm wondering why the check engine light *wouldn't* be on. I turn the key on and I can't see the check engine light illuminated on the dash. I'm not real familiar with HHR dashes so I'm attaching a pic.

I'm wondering if there is serious wiring issues in this car and someone just disabled the check engine light? Am I dealing with a lemon? What is her possible recourse if something serious is wrong with this car?

 

Possibly then CEL fuse is burnt out or removed, the wire is just visible here to the lower right of the air filter box

 

Welcome..

 

Yay, thank you! Ok I found the MAF wire and plugged it back in. Will clear codes and see where that leaves me.

I didn't see any fuse which was the CEL fuse. Online they were talking about #29 but in that instance the diagnostic port wasn't working either. My #29 is fine.

 

The diagnostic port is powered by the cigarette/power port fuse.

 

Thanks. Depending on how much HHR work I end up doing I may turn into a forum regular :).

Test drove it. Still getting hard shift in low gears but seems to have gotten rid of my previous two codes and now I have P0171. But it looks like somebody took the airbox off and didn't put it back on right. I'll be able to undo it and get it fixed tomorrow in the daylight.

 

The hard shifts are most likely a result of the trouble codes. That was GM's sneaky way of programming it to shift hard to alert you that a problem is detected in the OBD system.
Certain codes stored will trigger the hard shifting. Fix those and the shifts should return to normal.

 

Time to clean the MAF sensor, use the correct spray cleaner for the job.

https://www.obd-codes.com/p0171

 

And yes, the airbox/filter can cause P0171 (along with a lot of other things).

If it is still under the "certain national used car chain" warranty take it back. If not address it anyway. A non functioning CEL is a safety issue, most states it is a reason to flunk inspection.

 

Is it possible that you are seeing pending or historic codes? They would not light the CEL.