Check Engine Light

[cmm47172]

My 2009 Aveo 5 has a check engine light on. I checked it with a scanner and got a code p0138. What is this?
Someone told be it was an oxygen sensor. If that's true, which sensor is it? how many sensors are on this car? Where are they located?
any help is appreciated very much.

[Daox]

This should answer all your questions:

OBD-II Trouble Code: P0138 Oxygen Sensor Circuit High Voltage (Bank1, Sensor2)

[cmm47172]

Awesome, thanks for the reply! Do you know the part number for this thing. Can I get access to the part from the engine compartment or do I need to raise the car up to get access from the underside?

[Daox]

You'll have to get to it from the underside. It'll be the only thing in the exhaust pipe with a wire going to it after the catalytic converter.

[cmm47172]

Does any one know what a P0140 code means?
I cleared the P0138 code with my scanner back on the 4th just to see if it would come back and it did three days later.
I checked it this morning with my scanner and saw two instances of P0138 and now I'm also seeing a P0140 code. Is this another sensor going bad or could the re-appearance of P0138 have caused P0140 to trigger?
If P0140 is referring to the other sensor, should I replace the one that triggered the P0138 first to see if P0140 comes back?

[avguy]

You should get into the habit of searching (Google) for information on these codes before posting questions on forums. Sometimes the searches don't give you enough information, and need to be followed up with questions. But in this case, it's completely clear from the high level information on those codes that the 138 and 140 both point directly to the downstream O2 sensor being bad.

[cmm47172]

You should get into the habit of searching (Google) for information on these codes before posting questions on forums.

ouch, that hurt.

[2010AveoLT]

okay, a P0140 is Bank 1 Sensor 2 Insufficient Activity. its almost like you are fighting the EXACT Opposite of My Problem (I have a P0137-B1S2 Low Voltage, and a P2270-B1S2 Stuck Lean) if you'd like, I can PM you the Diagnostic Sheets I've been using for my own car, as well as any of the Related Connector Pinouts you might need.

[gothstone]

There really isn't any need for complicated diags here. Unless you see an obvious issue with the wires leading to the post cat O2 sensor, just replace the thing. 2009 CHEVROLET AVEO Oxygen Sensor

[2010AveoLT]

There really isn't any need for complicated diags here. Unless you see an obvious issue with the wires leading to the post cat O2 sensor, just replace the thing. 2009 CHEVROLET AVEO Oxygen Sensor

do you Know HOW MUCH a 09+ Oxygen Sensor Costs at a Parts House? ITS ON PAR with the price you'd get if you waltzed into a GM Dealership Parts Department ($250)! Throwing VERY EXPENSIVE Parts at a Problem and seeing what sticks IS NOT the Proper Way to Fix a Car. it DOES NOT Fix the ROOT CAUSE of the Problem. and don't get me wrong, RockAuto is Fine for lots of different parts, but in some Instances like if your Vehicle Registration was Tied to your Emissions Test (like in California, New York, and some parts of Indiana (where the OP is From) you need those emissions parts VERY QUICKLY.

I've done Research on how GM wired the Downstream Oxygen Sensor in the 09+ cars, and the Downstream Oxygen Sensor Circuit is a LOT MORE Complicated than you think. They actually routed the signal THROUGH the UBEC (Underhood Bussed Electrical Center AKA the Underhood Fuse Box) to the sensor from the PCM, and the run the Return Signal pretty much along the Same path on a Different wire BACK Through the UBEC and back to the PCM.