Code

Circuit or Sensor

13

Oxygen Sensor Circuit

14

Coolant Sensor Circuit (High)

15

Coolant Sensor Circuit (Low)

16

Ignition Pblms (Used on 1992-1996 models only)

21

Throttle Position Sensor (TPS) (High)

22

Throttle Position Sensor (TPS) (Low)

23

Intake Air Temperature (Low)

24

Vehicle Speed Sensor (VSS)

25

Intake Air Temperature (High)

26

Quad Driver Module Number 1

27

Quad Driver Module Number 2

28

Quad Driver Module Number 3

32

Exhaust Gas Recirculation Circuit

33

Mass Air Flow Sensor Circuit (1985-1990)

33

Manifold Absolute Pressure High (1984)

34

Mass Air Flow Circuit (1985-1990)

34

Manifold Absolute Pressure Low (1984)

35

Idle Air Control Circuit (IAC)

36

Mass Air Flow Burn Off Circuit

41

Cylinder Select Error Circuit (1985-1991)

42

Electronic Spark Timing Circuit (EST)

43

Knock Sensor Circuit

44

Lean Exhaust Present

45

Rich Exhaust Present

46

VATS Anti Theft Circuit Fault

51

PROM/EEPROM Error

52

Oil Temperature Circuit (Low Temperature)

53

System Charging Voltage High or Low

54

Fuel Pump Circuit (Low Voltage)

55

Engine Running Lean

62

Oil Temperature Circuit (High Temperature)

63

Oxygen Sensor Circuit (Open)

64

Oxygen Sensor Circuit (Lean Exhaust)

65

Oxygen Sensor Circuit (Rich Exhaust)

66

Air Conditioner Pressure Limit Exceeded

67

Air Conditioner Pressure Limit Exceeded

68

Air Conditioner Relay Fault

69

Air Conditioner Clutch Fault

72

Gear Selector Switch Fault (Start Lockout)

Code

Possible Fault (From most likely to least likely)

13

Check wiring and connectors. Bad Sensor

14

Check wiring, connectors, thermostat. Monitor actual engine temperature. If within limits, and wiring/connector is OK, change thermostat and/or sensor.

15

See above, particularly thermostat

16

Direct Ignition (DI) Fault

21

Sticking or Misadjusted TPS. Also check wiring/connectors. Adjust/replace TPS.

22

Sticking or Misadjusted TPS. Also check wiring/connectors. Adjust/Replace TPS.

23

Measure sensor resistance with Digital Ohm meter. Must not be 0 ohms or infinite ohms. Replace if it shows one of these readings. Check wiring/connector of sensor. If OK, replace sensor.

24

Only valid if vehicle moving. Check connections at ECM Check TPS setting. Possible ECM failure.

25

Measure sensor resistance with Digital Ohm meter. Must not be 0 ohms or infinite ohms. Replace if it shows one of these readings. Check wiring.connector of sensor OK.

26

Check EGR, Canister Purge and AIR pump relays with a digital Ohm meter. A resistance of less than 18 ohms indicates a bad relay. If OK, potential ECM failure.

27

Potential ECM or on a manual transmission car, potential upshift relay problem. Check relay, replace if less than 18 Ohms using a digital Ohm Meter.

28

Air conditioning Clutch relay and/or cooling fan relays. Check with digital Ohm meter, replace if less than 18 Ohms. If relays OK, potential ECM failure.

32

The most common cause of this code is a bad or intermittent EGR switch which is located on the EGR pipe between the exhaust manifold and the intake manifold. Replace this switch first when you get this code. Next, check electrical connections at EGR valve solenoid and then the ECM. Check all vacuum lines for leaks especially around the EGR valve. Possible ECM failure.

33

(1985-1990) Inspect intake system for leaks, Inspect for vacuum leaks, Check MAF connector and wiring, Check MAF for open using digital Ohm meter. Possible ECM failure.

33

(1984) Check vacuum hoses. Check wiring to sensor. Change sensor. Check connections at ECM.

34

(1985-1990) Clean the throttle body. Check MAF connections. Replace MAF relay. Replace MAF Sensor. Possible ECM failure.

34

(1984) Check Vacuum hoses associated with MAP sensor. Check wiring and connections, particularly at ECM. Replace the sensor. Possible ECM failure.

35

Check fuel pressure, injectors, leaking throttle body. Change the IAC valve.

36

Check connections at MAF, MAF relay and MAF Burn off relay. Check resistance of MAF relay and MAF burnoff relay with digital Ohm meter. replace if less than 18 Ohms. Possible ECM failure.

41

Check wiring at ECM. Possible PROM failure, or incorrectly seated PROM. Reseat PROM. Possible ECM failure.

42

Check wiring at ignition module. Replace ignition module. Possible ECM failure.

43

Check ECM wiring. Replace knock sensor

44

Check wiring.connectors at Oxygen sensor. Check fuel pressure. Replace Oxygen sensor.

45

Check evaporative charcoal canister for smell of fuel (which normally comes from filling fuel tank to full). check fuel pressure regulator. Possible leaking fuel injector or sticking/bad EGR valve. Possible bad Oxygen sensor.

46

With negative battery lead disconnected and using high pressure, non residue contact spray cleaner, spray into area where ignition key inserts followed by inserting and removing key several times. Check for open/short on harness from steering column VATS ignition key to ECM. Possible defective anti-theft module.

51

Faulty or incorrect PROM in the ECM. Change PROM with correct version for automobile.

52

Check connections at the oil temperature switch. If OK, replace switch.

53

If voltage is more than 17.1 or less than 10 volts, this code will be set. Check battery leads, alternator drive belt for tightness and have electrical shop check alternator output. Voltage with engine off should be 12 volts. Voltage with engine running should be 14-15 volts. Use digital volt meter for checks and measure at the battery terminals.

54

Using digital Ohm meter, check fuel pump circuits for shorts or opens.

55

This code is set when there is not enough fuel when accelerating. A possible fuel pump failure or insufficient fuel pressure due to a fuel line restriction is indicated.

62

Check wiring associated with Oil temperature switch. Replace switch.

63

Check wiring and connections to Oxygen sensor.

64

Check wiring and connections from Oxygen sensor to ECM. Check ECM ground terminal and battery ground. Check fuel pressure and fuel pump. Replace Oxygen sensor if all of above OK.

65

Check evaporative charcoal canister for fuel fumes. Replace if contaminated. Check oil for presence of fuel. Check fuel pressure regulator, fuel pump, check for leaking injectors, Check for stuck/defective EGR valve, Replace Oxygen sensor if all above OK.