2002 Saturn SL2 Error Code PO137 02 Sensor

THELJ

MEMBER
2002 SATURN

2002 Saturn SL2 with 56520 mi. I'm reading an error code PO137: O2 Sensor Circuit Low Voltage Bank 1 Senor 2. I purchased a new 02 sensor for the manifold, but wasn't convinced to which sensor this code is referring. Is it the one in the manifold or aft of the converter? I checked voltage out of the manifold O2 sensor with the sensor over 600 deg. F. Per my IR thermometer and got 0.82VDC, which was ok according to my Haynes manual (range of 0.1 - 0.9VDC). I then checked for a reference voltage at the electrical connector and only got 0.18VDC (should be approx 0.5VDC with ignition on and engine not running). Is this low reference voltage my problem, or am I chasing the wrong 02 sensor? Thanks for your help.

2 Replies

ZIPOTA1

MEMBER
5 POSTS

Hi,

I'm not sure if I'll be able to help you, but when I recently bought an 02 sensor for my Hyundai 96 it was easier to know which one I needed. The Hyundai dealer asked if I needed the upstream or downstream 02 sensor. I phoned the shop where I took my car to have it scanned. They said it was usually the upstream one that is faulty (now I'm not really sure if the upstream one is the one after the catalytic converter or the one before the manifold). All I told the Hyundai dealer was that I needed the upstream one and they knew which one it was. Now I guess it gets trickier if your car has many more than two 02 sensors. Mine only has 2.