2000 Cadillac STS PO 155 O2 sensor heater circuit malfuncti

Tiny
DANIELHODG
  • MEMBER
  • 2000 CADILLAC STS
  • V8
  • FWD
  • AUTOMATIC
  • 200,000 MILES
I have this code coming up, I have replaced the O2 sensor and the code is still coming up.
I can only suspect that there is a wiring issue or I changed the wrong sensor ( wrong bank ) the one closest to the fire wall.
Friday, March 5th, 2010 AT 8:30 AM

1 Reply

Tiny
FACTORYJACK
  • MECHANIC
  • 4,159 POSTS
I am showing P0155 as a failure with the bank 2 sensor 1 O2 sensor, this one be the one in the front bank exhaust manifold. If you changed the one in the rear manifold, closest to the firewall, and more than likely serviced from the top, that was bank 1 sensor 1. I do believe however, that they are the same sensors, so if you haven't roughed up the one you removed, you can reuse it. A simple way that I have found to check these, is to check the resistance of the sensor heater element, it would be across sensor terminals c and d. The corresponding harness side wires would be pink(D), and brown(C). I don't have a spec range, but it should not be open circuit, which the failed ones usually are.
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Friday, March 5th, 2010 AT 11:31 PM

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