Contour Enthusiasts Group Archives Forums General Troubleshooting Hooray for P1151

I was on my way up to ESU, and my cel came on. there was no immediate problem, BUT i pulled over and used my code reader (was in the glove box). I got P1151.

The car was idling high as well. I turned it off, and back on and ran the reader again. then erased the code. The idle came back down.

I drove the last 30 miles and it didn't come back.

Does this mean I need to replace my 02 or not? I get crappy mileage (17mpg) and and once and a while i get lean codes in both banks.

could this be the problem?

If you have more than 100K miles on the O2 sensor, yes, try replacing it.

From TSB,

Diagnostic Trouble Code Description Possible Causes
P1151 - Lack of HO2S-21 Switch (Bank 2-Radiator side Upper Sensor
Fuel Trim at Limit. The HEGO Sensor is monitored for switching. The code will set when the HO2S fails to switch due to circuit or fuel at or exceeding a calibrated limit.

Electrical:
�· Short to VPWR or VREF in harness or HO2S
�· HO2S circuit shorted to Ground
�· Water in harness connector
�· Open circuit
�· Corrosion or poor mating terminals and wiring
�· Damaged HO2S
�· Damaged PCM (other DTCs should be present)

Fuel System:
�· Excessive fuel pressure (stuck fuel pressure regulator, restricted fuel return lines, etc.)
�· Leaking/contaminated fuel injectors or fuel pressure regulator
�· Low fuel pressure or running out of fuel (fuel pump concern, fuel supply line restrictions, low fuel level, etc.)
�· Vapor recovery system (stuck VMV, etc.)

Induction System:
�· MAF contamination
�· Air leaks between MAF and throttle plate
�· PCV system / Other vacuum leaks
�· Improperly seated engine oil dipstick

EGR System:
�· Leaking gasket
�· Stuck EGR valve / Leaking diaphragm or EVR

Base Engine:
�· Oil overfill
�· Incorrect cylinder compression
�· Exhaust leaks before or near the HO2S
�· Secondary air stuck on

sounds like alot of the stuff I've done when I get the 2 lean codes in both banks.

I believe it maybe time to just put in a new sensor.

Or at least pull out the old one and take a look at it for a visual inspect.

Edit: I might also pull off the DPFE sensor and swap with the one I got from the junkyard. It's always been a suspect.