Trouble CodesGM OBD Trouble CodesGM Code 45

CODE 45- Rich Exhaust

Trouble Code 45 indicates that the O2 sensor is showing a persistently low exhaust oxygen content (rich), despite the efforts of the ECM to decrease injector on-time (thus decreasing fuel delivered). Integrator and BLM numbers may indicate < 128 by a substantial margin.

The conditions for setting this code are:

  • no Code 34 or Code 35 (MAF error) present, and
  • the O2 sensor voltage remains above 752 mV, and
  • the ECM is in Closed Loop control, and
  • throttle position is < 2 percent or > 20 percent, and
  • the above conditions exist for more than 20 seconds.

Typical causes for this code include:

1) O2 sensor defective or contaminated (if incorrect RTV sealant or too much RTV is used, this may happen)
2) Leaking fuel injectors
3) Fuel pressure too high
4) EMI interference from poor plug wires
5) Evaporative Emission system defect
6) TPS and/or EGR problem
7) MAF sensor reading higher airflow than is actually present

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Chevy Trouble Codes