Chevy & GMC Vans

Hi All, As the topic says I am having a SES of P0155 Heating circuit Bank 2 Sensor 1. I changed out the sensor behind the cats, cleared the code and it came back. I think this is the right sensor? I'm hoping a couple of you would have some in depth trouble shooting methods on why this code keeps coming back.

As per your topic 'bank 2 sensor 1' you have replaced the wrong sensor.

Positions are as follows:
Bank 1 - the bank which contains the cylinder # 1 (drivers side)
Bank 2 - the bank which contains the cylinder # 2 (passenger side)
Sensor 1 - the 1st sensor in the particular bank
Sensor 2 - the 2nd sensor in the particular bank
If the vehicle has a y-pipe, like the Astro/Safari (2 banks into 1 cat convertor) you would just have 1 # 2 sensor & would be classed as Bank 1, sensor 2.

The sensor you replaced was the Bank 1, sensor 2. Replace the passenger side sensor before the cat convertor - once you make sure that the power (pink wire) is good to the connector. The ground (light green) is controlled by the PCM & requires a scan tool to control it.

Thank you Jim for the info. Time to do some O2 sensor swapping then.

Something I noticed on my gauge that I picked up. The Gauge didn't display any voltage or activity from that B2S1 with the Heater fault. Does the EMC go into a default ignore mode when that code comes up? The other 2 sensors read ok.

e7ats wrote: Thank you Jim for the info. Time to do some O2 sensor swapping then.

Something I noticed on my gauge that I picked up. The Gauge didn't display any voltage or activity from that B2S1 with the Heater fault. Does the EMC go into a default ignore mode when that code comes up? The other 2 sensors read ok.

That is the front oxy sensor on bank #2,NOT WORKING, ( it should be cycling between .2 -.8 of a volt ) which is before the cat and is most critical for your fuel mixture.

If I were you, I would replace both ( Bank 1 and Bank 2 FRONT #1 oxygen sensors ) for performance and effecient gas milage / and balanced engine effeciency.

on that note how often are you supposed to replace O2 sensors anyways?

Cobra wrote:on that note how often are you supposed to replace O2 sensors anyways?

Short answer is, whenever they are bad!

To really make a good decision on that requires testing the O2 sensor operation with a lab scope & checking the switch rate, rise & fall times & cross over counts. The newer the vehicle the more monitoring the computer can do of the O2 sensor to determine the effectiveness of an O2 sensors operation. Good rule of thumb, replace the sensor if you get a code indicating a fault with the O2 sensor. Aside from that, it is either a gamble to see if it pays off or you have to do some technical testing of the sensor.

I would replace them at 100k miles as preventative maintenance, if it were my van.

Follow up.

I change both bank 1 and bank 2, sensor 1 and that fixed the code. I do notice a bit more response from the engine. I am going to make a How To on changing these out. Maybe. I still owe an update on my new gauge.

Just some additional info I found from that link Darren posted in his OBD thread...
http://www.obd-codes.com/p0155