Reset computer, if it comes again, check the common causes for both codes and start troubleshooting from those. Good luck. It could be something as simple as water in the harness connector (this can happen if you have been driving in the pouring rain and water drips on the connector).
From TSB.
P0155 - Bank 2 (Radiator side) Upper HO2S Sensor Heater Circuit Malfunction (HO2S-21)
During testing, the HO2S heaters are checked for opens/shorts and excessive current draw. The code will set when current draw exceeds a maximum calibrated limit or falls below a minimum calibrated limit and/or an open or short is detected.
�· Blown fuse
�· Short to VPWR in harness or HO2S
�· Water in harness connector
�· Open VPWR or GND circuit
�· Low battery voltage
�· Poor electrical connections from PCM to HO2S sensor
�· HO2S heater
�· PCM
P1151 - Lack of HO2S-21 (radiator side upper sensor) Switch, Indicates Lean
When an HO2S sensor indicates lean at the end of a test, the system is trying to correct for an over-lean condition. The code is set when the fuel control system no longer detects switching for a calibrated amount of time. 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
Last edited by Tony2005; 11/05/05 03:17 AM.
