Non-Monitored Circuits, Systems and Conditions

NOTE: The conditions below may not set Diagnostic Trouble Codes (DTC's) which correspond to the circuit involved. However these conditions may cause driveability problems and/or cause DTC's to be set for other circuits or systems.

- Example: A fuel pressure problem will not register a trouble code directly, but could cause a rich or lean oxygen sensor code to be set.

Secondary Ignition - The PCM cannot detect an inoperative ignition coil, fouled or worn spark plug, ignition cross fire, or open spark plug cable. [1]


Engine Timing - The PCM cannot detect an incorrectly indexed timing chain, camshaft sprocket, crankshaft sprocket or distributor.


Fuel Pressure - Fuel pressure is controlled by the vacuum-assisted fuel pressure regulator. The PCM cannot detect a clogged fuel pump inlet filter, clogged in-line fuel filter, or a pinched fuel supply or return line. [1]


Fuel Injectors - The PCM cannot detect a clogged fuel injector, stuck fuel injector pintle, or incorrect type fuel injector. [1]


Fuel Requirements - Poor quality gasoline can cause hard starting, stalling, and stumble. Use of methanol-gasoline blends may result in starting and driveability problems.

PCM Grounds - The PCM cannot detect a poor system ground. However, a Diagnostic Trouble Code may be stored in the PCM as a result of this condition.


Throttle Body Air Flow - The PCM cannot detect a clogged or restricted air cleaner inlet or filter element. [1]


Exhaust System - The PCM cannot detect a plugged, restricted, or leaking exhaust system. [1]


Cylinder Compression - The PCM cannot detect uneven, low, or high engine cylinder compression. [1]


Excessive Oil Consumption - Although the PCM monitors the exhaust stream oxygen content through the oxygen sensor when the system is in a closed loop, it cannot determine excessive oil consumption.


Evaporative System - The PCM cannot detect a restricted, plugged, or loaded evaporative canister. [1]


Vacuum Assist - Leaks or restrictions in the vacuum circuits of vacuum-assisted engine control system devices are not monitored by the PCM. These could result in a MAP sensor message being stored in the PCM. [1]


REMARKS

[1] Any of these conditions could result in a rich or lean condition causing an oxygen sensor trouble code to be stored in the PCM, or the vehicle may exhibit one or more of the driveability symptoms listed in TEST NTC-1A.