P0155 - 02 Sensor Heater Circuit Malfunction (Bank 2 Sensor 1)
01-10-2010, 10:59 PM
#1
MBWorld Fanatic!
Thread Starter
P0155 - 02 Sensor Heater Circuit Malfunction (Bank 2 Sensor 1)
Hey guys,
At the track time before last I used some higher octane gas than usual and I threw this code afterwards. P0155 - 02 Sensor Heater Circuit Malfunction (Bank 2 Sensor 1). After looking it up online this is the description of the CEL.
During idle I've been getting a slight fluctuation in my AFR's, ranging from 15.2 - 14.3. Could this cause a fluctuating idle? I'm thinking my O2 sensor has gone bad and I plan on replacing it either way.
At the track time before last I used some higher octane gas than usual and I threw this code afterwards. P0155 - 02 Sensor Heater Circuit Malfunction (Bank 2 Sensor 1). After looking it up online this is the description of the CEL.
This code refers to the front oxygen sensor on Bank 2. The heated circuit in the oxygen sensor decreases time needed to enter closed loop. As the O2 heater reaches operating temperature, the oxygen sensor responds by switching according to oxygen content of the exhaust surrounding it. The ECM tracks how long it takes for the oxygen sensor to begin switching. It the ECM determines (based on coolant temp) that too much time elapsed before the oxygen sensor began operating properly, it will set P0155
01-10-2010, 11:45 PM
#2
Did you use leaded gas? Leaded race gas kills O2 sensors pretty quick. But by pretty quick, I mean 10,000 miles for a brand new sensor versus 100,000 miles for the same sensor running only unleaded. Still, one tank of leaded gas shouldn't have crippled the sensor unless it was moments away from death already. Who really knows I guess.
That fluctuation doesn't seem terribly extreme to me if you're reading off of a narrow band sensor. A standard narrow band O2 will bounce around pretty good almost all the time. I also didn't think OEM ECU's did any closed-loop A/F correction at idle. Maybe these cars are different. One of the tuners on here would be able to answer definitively. That said, if it doesn't do any idle A/F correction, it's not the sensor causing this fluctuation.
That fluctuation doesn't seem terribly extreme to me if you're reading off of a narrow band sensor. A standard narrow band O2 will bounce around pretty good almost all the time. I also didn't think OEM ECU's did any closed-loop A/F correction at idle. Maybe these cars are different. One of the tuners on here would be able to answer definitively. That said, if it doesn't do any idle A/F correction, it's not the sensor causing this fluctuation.
