Technical Information ECU Problem Codes

What are ECU problem codes?

ECU problems codes are diagnostic outputs from the ECU, used to indicate in what area a problem lies. Usually the check engine warning light (on the dash) will come on for a serious problem, but will not necessarily come on for a minor problem. The ECU will remember problem codes with the ignition off; 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.

Pre OBDI ECUs
To read the codes, turn the ignition on and look at the LED inside the ECU. The LED is visible through a small plastic window in the top of the ECU. The ECU can signal simultaneous problems by blinking separate codes, one after the other. Problem codes 1 - 9 are indicated by 1 - 9 flashes, problem codes over 9 use one long flash as ten short flashes.

 

OBDI and later ECUs
Find the  diagnostic connector, which is a two wire blue connector found near the passengers feet, or in the centre console.
Short out the diagnostic connector with a piece of wire.  The check engine light on the dash will flash the problem codes.

Code Meaning
1 O2A - Oxygen sensor #1
2 O2B - Oxygen sensor #2
3 MAP - manifold absolute pressure sensor
4 CKP - crank position sensor
5 MAP - manifold absolute pressure sensor
6 ECT - water temperature sensor
7 TPS - throttle position sensor
8 TDC - top dead centre sensor
9 CYP - cylinder sensor
10 IAT - intake air temperature sensor
12 EGR - exhaust gas recirculation lift valve
13 BARO - atmospheric pressure sensor
14 IAC (EACV) - idle air control valve
15 Ignition output signal
16 Fuel injectors
17 VSS - speed sensor
19 Automatic transmission lockup control valve
20 Electrical load detector
21 VTEC spool solenoid valve
22 VTEC pressure valve
23 Knock sensor
30 Automatic transmission A signal
31 Automatic transmission B signal
41 Primary oxygen sensor heater
43 Fuel supply system
45 Fuel system too rich or lean
48 LAF - lean air fuel sensor
54 CKF - crank fluctuation sensor
58 TDC sensor #2
61 Primary oxygen sensor
63 Secondary oxygen sensor
65 Secondary oxygen sensor heater