SPN 4237, FMI 1 - Adaptive Learn Bank1 Low (Gasoline) Diagnostic Aids NOTE: If any other DTCs are present, diagnose those first. Oxygen Sensor Wire - Sensor may be mispositioned contacting the exhaust. Check for short to ground between harness and sensor and on sensor harness Injectors - System will be rich if an injector driver or driver circuit fails shorted-toground. The system will also be rich if an injector fails in an open. Fuel Pressure - System will be rich if fuel pressure is too high. Check fuel pressure in the fuel rail during key-on, engine off and during normal operating conditions. System Grounding - ECM and engine must be grounded to the battery with very little resistance allowing for proper current flow. Faulty grounds can cause current supply issues resulting in many undesired problems. If all tests are OK, replace the HO2S sensor with a known good part and retest.
Indmar Products
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All Rights Reserved Draft Rev. A-Jan. 2008
