Fault Code 51
Description: Oxygen sensor
output indicates lean too long
Power loss light: Off
Limp-in mode: Engine allowed to run rich, but prevented
from running lean
Bad oxygen sensor - Replace the sensor which is located on the turbo
housing near the down pipe (for turbo) or on the down pipe near the exhaust
Bad connection or wiring - Check the wiring and connections between
the sensor and the logic module (or SMEC). Clean and regrease any
corroded connectors with dielectric grease and repair any shorts.
Look for melted wire insulation near the exhaust manifold. A shorted
connection to ground or any positive source will cause this fault code.
Low fuel rail pressure - See the Diagnosing
Your Fuel System page.
- In closed-loop
- Sensor output indicates lean for more than 715 seconds (11 minutes,
Results If Component Fails
A fault code 51 is stored, the circuit stays in closed-loop, and the logic
module will still monitor the oxygen sensor signal. If the condition
persists for four times what it took to set the code, the logic module
will allow the engine to run rich, but prevent it from running lean.
This page is maintained by Russell W. Knize and was last updated 08/28/98.
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Copyright © 1996-2003 Russ W. Knize