Diagnostic Trouble Code Descriptions

CODE IDENTIFICATION
The "Service Engine Soon" light will only be "ON" if the malfunction exists under the conditions listed below. If the malfunction clears, the light will go out and the code will be stored in the ECM. Any Codes stored will be erased if no problem reoccurs within 50 engine starts.

Code 12 - No engine speed reference pulse.
PROBABLE CAUSE
No engine speed sensor reference pulses to the ECM. This code is not stored in memory and will only flash while the fault is present. Normal code with ignition "ON," engine not running.


Code 14 - Coolant Sensor High Temperature Indication
PROBABLE CAUSE
Sets if the sensor or signal line becomes grounded for 5 minutes.

Code 15 - Coolant Sensor Low Temperature Indication
PROBABLE CAUSE
Sets if the sensor, connections, or wires open for 5 minutes.

Code 21 - TPS Signal Voltage High
PROBABLE CAUSE
Throttle Position Sensor (TPS) circuit voltage high (open circuit or misadjusted TPS). Engine must run 30 seconds, at curb idle speed, before this code will set.

Code 22 - TPS Signal Voltage Low
PROBABLE CAUSE
Throttle Position Sensor (TPS) circuit voltage low (grounded circuit). Engine must run 2 minutes at 1250 rpm or above before this code will set.

Code 23 - TPS Not Calibrated
PROBABLE CAUSE
Throttle Position Sensor (TPS) circuit. Voltage not between 0.25 and 1.3 volts at curb idle speed. Engine must run for 30 seconds, at curb idle, before this code will set.

Code 24 - VSS No Vehicle Speed Indication
PROBABLE CAUSE
Vehicle speed sensor (VSS) circuit (open or grounded circuit). Vehicle must operate at road speed for 10 seconds before this code will set.

Code 31 - MAP Sensor Too Low
PROBABLE CAUSE
Absolute Pressure (MAP) circuit signal voltage too low. Engine must run at curb idle for 10 seconds before this code will set.

Code 32 - EGR Loop Error
PROBABLE CAUSE
Exhaust Gas Recirculation (EGR) vacuum circuit has seen improper EGR vacuum. Vehicle must be running at road speed approximately 30 mph (48 Km/h) for 10 seconds before this code will set.

Code 33 - MAP Sensor Too High
PROBABLE CAUSE
Absolute Pressure (MAP) circuit signal voltage too high. Engine must run at curb idle for 10 seconds before this code will set.

Code 51 - PROM
PROBABLE CAUSE
Faulty or improperly installed PROM. It takes approximately 10 seconds before this code will set.

Code 52 - ECM
PROBABLE CAUSE
Fault in ECM circuit. It takes 10 seconds before this code will set.

Code 53 - Five volt Reference Overload
PROBABLE CAUSE
5 volt reference (Vref) circuit overloaded (grounded circuit). It takes 10 seconds before this Code will set.