Some background: 08 HHR with a blown flex joint. Intermittent CEL (clear it and it wouldn't come back for months - figured it was related to the downstream sensor not getting exhaust). Drove it like this for two-3 years, car runs fine. Did a temp fix by clamping in a part I got from ZZPerformance and a new downstream 02 sensor. Drove it i81500 miles and welded the part on in my dad's garage. Started car, smooth and quiet, sounded like factory. Cleared codes.... engine dies. Won't restart. Two more cranks and the engine starts - CEL on. Cleared again, car dies.

Here are the codes:
P0030 - H02S Heater control circuit Bank 1 sensor 1
P0036 - H02S Heater control circuit Bank 1 sensor 2
P0053 - Powertrain - HO2S Heater Resistance
P0102 - Powertrain - Mass or Volume Air flow circuit low input

Pending codes:
B2AAA - meaningless code
P0054 - Powertrain Heater Resistance Sensor 2
P0135 - Powertrain 02 Sensor Heater Circuit bank 1 sensor 1
P0141 - Powertrain 02 Sensor Heater Circuit Bank 1 sensor 2
P0443 - Powertrain Evap Emissions control system purge control valve circuit


Keep in mind that *the car runs fine*. NO misfires, no hesitation, no rough idle, no stumbling, great gas milage (over EPA estimates, per the DIC) and as much power as when it was new. The only time I have a problem is when I clear the codes. If I do it while running, it'll stumble, hesitate and die. If I do it while off, it won't start till it decides to and the CEL is back on.

I am very confused. I don't want to start throwing parts and money at it and hoping it helps (replaced one 02 sensor already), and anyway based on what I've found on the net, it shouldn't even be *running* with these codes set, much less running as good as it does! Thanks!

 

Well, you apparently thought you didn't need to plug things back in. Or check the fuses. Or check for wires on hot things.

When you the codes are present the computer goes into "open loop", which means it is not controlling the air fuel mixture. After you clear them it goes into "closed loop" the computer is in control, with faulty data.

There is a chance that your cat is destroyed from long term abuse.

 

Connectors looked good, but I will recheck them, and I made sure wires were well away from the things that can melt them.

The cat hasn't seen exhaust in about 3 years, the flex pipe was completely disconnected from the rest of the system. (Setting off car alarms and making v8 drivers insecure is fun) It's only been in use since December.

I never even thought to check fuses. I will do that this weekend.

Wouldnt open loop mode cause poor performance and gas mileage, though? I recently drove it from Utah to NM and averaged 32mpg.

 

BTW, B2aaa is not meaningless. I means your code reader is too old.

The fuse marked EXH #33 under hood is probably blown ; that covers the O2 sensor heaters, the EVAP and the MAF / IAT.

 

My code reader is a Bluetooth elm327 unit and Torque Pro on my phone. Hasn't been updated in a while, so that makes sense.

It's currently 4am where I am, so I'll be checking fuse #33 when it gets light out. Will update after that.

Thanks!

 

Load test the battery.
You have the codes, but probably not, if your reader is out of date.
I suggest a battery lobotomy, disconnect the negative cable at the battery for a full 30 minutes.
while it’s disconnected, do not close the hatch!
inspect ground wires are they clean and tight?
inspect for loose connections.

 

The battery has been replaced in the past year - the one from Texas did NOT like a Utah winter! Battery voltage looks good via Torque, and I don't have anything added to the electrical system, no subs or amps or extra lighting, not even a phone charger. As soon as the sun comes up, I'm going to start checking fuses and connectors.

 

I like Torque a lot, but the best test of a battery is to shut the car off, leave it sit for 10 minutes or more, then put a volt meter directly on the posts. It should read 12.7 volts or higher. Any lower and the battery is suspect. Yes, even a 1 year old battery can fail.

 

I just replaced the #33 EXH fuse. Started car, cleared CEL. Car stayed running! No pending codes, CEL stayed off for 3 start cycles. My gf is gonna drive it to work so I'll have her watch for the cel to come on. If it does, I'll check the fuse again, if it's blown, I'll start chasing wires and connectors.

Now, to fix my key fob....



Thanks all!

 

Here is a suggestion, start here. Computer is probably thinking, "I don't know what to do".