2004 Ford Mondeo DIAGNOSTIC CODE

Heated oxygen sensor/s

P1150/1151 OBD Trouble Code

Technical DescriptionLack of HO2S-21 Switch, Sensor Indicates Lean

What does that mean?A Heated Exhaust Oxygen (HO2S) sensor indicating lean at the end of a test is trying to correct for an over-rich condition. The test fails when the fuel control system no longer detects switching for a calibrated amount of time.

SymptomsYou will likely not notice any drivability problems.

CausesA code P1151 may mean that one or more of the following has happened:

Electrical:
Short to VPWR in the harness or HO2S
Water in the harness connector
Open/shorted HO2S circuit
Corrosion or poor mating terminals and wiring
Damaged HO2S
Damaged PCM
Fuel System:
Excessive fuel pressure
Leaking/contaminated fuel injectors
Leaking fuel pressure regulator
Low fuel pressure or running out of fuel
Vapor recovery system
Induction System:
Air leaks after the MAF
Vacuum Leaks
PCV system:
Improperly seated engine oil dipstick
EGR System:
Leaking gasket
Stuck EGR valve
Leaking diaphragm or EVR
Base Engine:
Oil overfill
Cam Timing
Cylinder compression
Exhaust leaks before or near the HO2S(s)