h30:
| Steps | Code 41 - HEGO indicated the fuel system
was lean for more than 15 seconds when the fuel system should have been
in closed loop fuel control
Code 42 - HEGO indicated the fuel system was rich for more than 15 seconds when the fuel system should have been in closed loop fuel control Code 43 - HEGO indicated the fuel system was lean at WOT for more than 3 seconds Code 65 - Never went to closed loop fuel control on HEGO switching Code 85 - Adaptive fuel has corrected an excessive rich condition. Adaptive fuel made the fuel system leaner. Code 86 - Adaptive fuel has corrected an excessive lean condition. Adaptive fuel made the fuel system richer. Before attempting to service a Continuous Memory Service Code 41, 42, 43, 65, 85 or 86, diagnose all other drivability complaints first. Examples, rough idle, misses, etc., in the EEC-IV Diagnostic By Sympton in the appropriate Engine Supplement Section. Whenever an over-rich fuel condition has been experienced (fuel fouled spark plugs), make a thorough check of the ignition system. If a HEGO sensor is suspected of being fuel fouled (low output or slow response), after the vehicle service, run the vehicle at sustained high speed (within legal limits) followed by a few hard accelerations. This will burn off the HEGO contamination and restore proper HEGO operation. The fuel Service code may help to isolate the cause of the fuel control problem. Some areas to check are: Code 41: Intermittent HEGO circuit (Signal or Ground) If Code 65 is also present, service faulty HEGO circuit (Signal or Ground) If Code 43 is also present, service Code 43 first. Airflow meter indicates low air flow. Check for vacuum leaks, intake air leaks, or a sticking air meter vane caused by contamination or frost. Low fuel pressure at WOT (low pressure fuel pump, restricted fuel supply via crimped fuel lines or plugged fuel filter) Low fuel flow at WOT with correct fuel pressure (clogged fuel injectors, low battery voltage) Code 42: Intermittent HEGO circuit (Signal or Ground) Airflow indicated by the air meter is greater than the actual airflow, which causes more fuel to be delivered than necessary. Check for high air meter voltage due to a sticking air meter vane caused by contamination Excessive fuel pressure. Check for fuel pressure regulator vacuum line disconnected or kinked fuel return line. Excessive fuel flow. Check for damaged or stuck open fuel injector(s) Both Codes 41 and 42: Intermittent HEGO circuit (Signal or Ground) Sticking air meter vane due to contamination Contaminated HEGO sensor (lead or silicone fouled) Code 43: Low fuel pressure (low pressure fuel pump, restricted fuel supply via crimped fuel lines or plugged filter) Low fuel flow at WOT with correct fuel pressure (clogged fuel injectors, low battery voltage) Code 65: Check for a faulty HEGO circuit (Signal or Ground) Code 85: If Code 42 is also present, service Code 42 first Excessive fuel pressure. Check for fuel pressure regulator vacuum line disconnected or kinked fuel return line Excessive fuel flow. Check for damaged fuel injector pintle or injectors stuck open. Code 86: If Code 41 is also present, service Code 42 first Low fuel pressure (low pressure fuel pump, restricted fuel supply via crimped fuel lines or plugged filter) Low fuel flow with correct fuel pressure (clogged fuel injectors, low battery voltage) |
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