CEL Codes and How to Check

[RedRacer]

What are ECU problem codes, also called CEL codes? *CEL = Check Engine Light.

ECU problems codes are diagnostic outputs from the ECU, used to indicate in what area a problem lies. Usually the check engine warning light comes on for a serious problem, but will not necessarily come on for a minor problem. The ECU will remember problem codes even with the ignition off; and the only way to clear the codes is to disconnect the battery or remove the hazard fuse for half a minute or so.

How to read ECU codes?

Find the diagnostic connector, which is a two wire blue/grey/green connector found near the passengers feet, or in the center console (Each car may differ) Click link for image of connector and paperclip jumper:

http://home.mindspring.com/~redracer95/stuff/id24.html

Short out the diagnostic connector with a piece of wire, e.g. a paper clip bent to a U-shape, etc. To read the codes, turn the ignition on.

The check engine light on the dash will flash the problem codes. If there is more than 1 problem, a different code will subsequently follow the first after a brief pause.

There are two types of flashes - short and long, which are combined to represent number codes. Each short flash indicates 1 unit and each long flash represents 10 units. Problem codes 1 - 9 are indicated by 1 - 9 flashes, problem codes 10 - 90 use 1 - 9 long flashes. If the code is more than 9, the long flashes will start first before the short ones. The codes will continue to repeat as long as your ignition is on.



Code and Meaning
1 "Oxygen Sensor ""A"" (Primary)"
defective circuit or unplugged / defective sensor

2 "Oxygen Sensor ""B"""
defective circuit or unplugged / defective sensor

3 MAP Sensor (Manifold Absolute Pressure)
defective circuit or unplugged / defective sensor

4 CKP Sensor (Crankshaft Position Sensor)
defective circuit or unplugged / defective sensor

5 MAP Sensor (Manifold Absolute Pressure)
mechanical problem / disconnected piping

6 ECT Sensor (Engine Coolant Temperature)
defective circuit or unplugged / defective sensor

7 TP Sensor (Throttle Position)
defective circuit or unplugged / defective sensor

8 TDC Sensor (Top Dead Center)
defective circuit or unplugged / defective sensor

9 CYP Sensor (Cylinder)
defective circuit or unplugged / defective sensor

10 IAT Sensor (Intake Air Temperature)
defective circuit or unplugged / defective sensor

12 EGR Lift Sensor (Exhaust Gas Recirculation)
defective circuit or unplugged / defective sensor

13 BARO Sensor (Atmospheric Pressure)
defective circuit or unplugged / defective sensor

14 IAC Valve (Idle Air Control)
defective circuit or unplugged / defective sensor

15 Ignition Output Signal missing or defective ignition output signal

16 Fuel Injector System defective circuit or unplugged / defective fuel injector

17 VSS (Vehicle Speed Sensor) defective circuit or unplugged / defective sensor

19 Automatic Transmission Lock Up Control Solenoid Valve
defective circuit or unplugged / defective solenoid valve

20 Electrical Load Detector defective circuit or unplugged
/defective sensor

21 VTEC Solenoid Valve defective circuit or unplugged
/defective solenoid valve

22 VTEC Oil Pressure Switch defective circuit or unplugged
/defective oil pressure switch

23 KS (Knock Sensor) defective circuit or unplugged / defective sensor

30 "Automatic Transmission Signal: ""A"" / SEAF / SEFA / TMA or TMB" defective circuit or unplugged / defective sensor

31 "Automatic Transmission Signal ""B""" defective circuit or unplugged / defective sensor

41 Primary Oxygen Sensor - Heater circuit malfunction

43 Fuel Supply System defective or malfunctioning fuel supply system

45 System Too Lean or Too Rich malfunction in the fuel monitoring systems

48 LAF Sensor (Lean Air Fuel) defective circuit or unplugged
/defective sensor

54 CKF Sensor (Crankshaft Speed Fluctuation) defective circuit or unplugged / defective sensor

58 TDC Sensor 2 (Top Dead Center) defective circuit or unplugged
/defective sensor

61 "Oxygen Sensor, Heated - Sensor 1 (Primary)"
"high voltage, low voltage, or slow response"

63 "Oxygen Sensor, Heated - Sensor 2 (Secondary)"
"high voltage, low voltage, or slow response"

65 Oxygen Sensor Heater (Secondary) malfunctioning or defective oxygen sensor heater

67 Catalyst system Efficiency Below Threshold malfunctioning or defective catalyst system

70 Automatic Transmission malfunction with the automatic transmission controls

71 Cylinder 1 Misfire or a Random Misfire a condition is present that is creating a cylinder misfire

72 Cylinder 2 Misfire or a Random Misfire a condition is present that is creating a cylinder misfire

73 Cylinder 3 Misfire or a Random Misfire a condition is present that is creating a cylinder misfire

74 Cylinder 4 Misfire or a Random Misfire a condition is present that is creating a cylinder misfire

75 Cylinder 5 Misfire or a Random Misfire a condition is present that is creating a cylinder misfire

76 Cylinder 6 Misfire or a Random Misfire a condition is present that is creating a cylinder misfire

80 Exhaust Gas Recirculation insufficient flow detected

76 ECT Sensor (Engine Coolant Temperature) circuit range
/performance problem

90 Evaporative Emission Control System leak detected in the fuel tank area

91 Fuel Tank Pressure Sensor low input

92 Evaporative Emission Control System insufficient purge flow[/img]