Trouble Code Identification

TROUBLE CODE IDENTIFICATION

Code No.

System Affected

Probable Cause

12 ⁽¹⁾

Ignition Ref. Signal

Dist. or Circuit, ECM

13 ⁽²⁾

O2 Sensor

Sensor/Circuit, ECM

14 ⁽³⁾

Shorted Coolant Temp. Sensor Signal

Sensor/Circuit, ECM

15 ⁽⁴⁾

Open Coolant Temp. Sensor Signal

Sensor/Circuit, ECM

21 ⁽⁵⁾

Idle (Vacuum) Switch & MAP Sensor

Switch/Circuit, ECM

22 ⁽⁶⁾

Fuel-Cut Solenoid

Relay/Circuit, ECM

Duty (Mixture Control) Solenoid Circuit

Solenoid Circuit, ECM

AIR Management Valve

VSV/Valve Circuit, ECM

Canister Purge VSV

VSV/Valve Circuit, ECM

Canister Purge VSV

VSV/Valve Circuit, ECM

31 ⁽²⁾⁽⁷⁾

Ignition Ref. Signal

Wiring Circuit, ECM

EGR System

EGR Valve, Thermal Vac. Valve or Backpressure Transducer

EGR Gas Temp. Sensor

Sensor/Circuit, ECM

44 ⁽²⁾⁽⁸⁾

O2 Sensor (Lean)

Mixture Control Solenoid, O2 Sensor, ECM

45 ⁽²⁾⁽⁹⁾

O2 Sensor (Rich)

Mixture Control Solenoid, O2 Sensor, ECM

Fuel-Cut Solenoid

Solenoid/Circuit, ECM

Faulty ECM RAM

ECM

AIR Management Valve

Valve or ECM

Mixture Control Solenoid

Solenoid/Circuit, ECM

Faulty ECM

ECM

⁽¹⁾	Code 12 is a normal response to key on and engine off with ALDL test lead installed.

⁽²⁾	Requires engine operation at part throttle under load for up to 5 minutes after engine reaches normal operating temperature to set code.

⁽³⁾	Engine must be running at least 2 minutes before code will be set.

⁽⁴⁾	Engine must be running at least 5 minutes before code will be set.

⁽⁵⁾

Code will set if one of following conditions exist: Engine speed is 200-1000 RPM and vacuum applied to MAP sensor is more than 20 in. Hg for 5 seconds; Idle switch is off and vacuum applied to MAP sensor is less than 4 in. Hg for 5 seconds.; Engine speed is greater than 1500 RPM and vacuum applied to MAP sensor is 16-18 in. Hg and idle switch is on for 5 seconds.

⁽⁶⁾	Engine must be decelerating and engine speed greater than 2000 RPM before code will be set.

⁽⁷⁾	No reference signal to ECM after 10 seconds at part throttle under load. Code will be stored in memory.

⁽⁸⁾	Engine speed must be less than 2500 RPM and exist for 5 seconds after fuel-cut recovery. Code will set except when vacuum reading to MAP sensor is less than 23 in. Hg, Code 13 or 21 is stored, or coolant temperature is greater than 302°F (150°C).

⁽⁹⁾

Engine speed must be less than 2500 RPM with vehicle speed of 12-50 MPH for more than 30 seconds after canister purge. Code will set except when vacuum reading to MAP sensor is less than 23 in. Hg, Code 13 or 21 is stored, coolant temperature is greater than 302°F (150°C) or under high altitude conditions greater than 8000 ft. (2434 meters).