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Code 45, Rich Exhaust Indication: Notes

NOTE: Test numbers refer to test numbers on diagnostic chart.
  1. System will return to "open loop" if O2 sensor cools off while engine is idling. Scan "loop" status often during testing. For intermittent condition, see INTERMITTENTS in TESTS W/O CODES article.
  2. This step causes a lean condition by putting an air leak into engine to see if ECM can respond. A drop in dwell indicates ECM and O2 sensor are not faulty. Look for source of constant rich condition.
  3. This step tests ECM response to a lean O2 signal (low voltage). If there is no dwell change with a grounded lead to O2 sensor terminal No. 9, fault is in ECM. Open O2 sensor circuit would have set Code 13.
  4. The system's response in step 2) indicates the exhaust is actually rich. This could be due to a reverse connected M/C solenoid or excessive fuel in the engine. If all checks are okay, service carburetor.
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