NG 900/9-3 Motronic CEL Flash Codes

Overview

The normally aspirated NG900's use a Motronic Engine Management System (EMS). When a Check Engine Light (CEL) shows, it indicates that there is a potential problem with the systems that are responsible for controlling the emmisions of the car. You can take it to the dealer and they will plug it into a computer to establish which part of the system is causing trouble, but if you want to get a rough idea of what the trouble is then you can use the following method.

Retrieving Codes

On the kick panel underneath the steering wheel, and in front of the pedals, you will see a rectangular piece of plastic. This is the socket that the dealer plugs their diagnostic equipment into. Remove the cover and you will see that it has two rows of 8 connectors (See below)

Motronic Flash Socket

1. Get a piece of insulated electrical wire and strip back the insulation about 5mm at each end. Insert one end of the wire into the socket for pin 6 (this is highlighted in red above)
2. Find a suitable place on the bodywork that you can ground the other end of the wire too (DO NOT ground it yet!)
3. Turn the ignition on and ground the wire for between 0.5 and 4 secs.
4. The CEL will now flash in two stages. Count the first set of flashes and then the second set. The two will make up the two digit number that you are looking for. e.g. 4 flashes followed by 1 flash equals 41.
5. Refer to the tables below to establish what the code means.

Motronic 2.10.2 (4 Cyl. engines)

Flash code  	Function
11 	            Relay, secondary air injection
12 	            No fault
21 	            Mass air flow sensor
41 	            Coolant temperature sensor
51 	            Throttle position sensor
61 	            Oxygen sensor
72 	            Adaptation, long time
73 	            Adaptation, short time
81 	            EVAP canister purge valve
91 	            Control module fault (RAM)
92 	            Control module fault (ROM) 

Motronic 2.8.1 (V6 Engines)

Flash code  	Function
11 	            Relay, secondary air injection
12 	            No fault
21 	            Mass air flow sensor
31 	            Intake air temperature sensor
41 	            Coolant temperature sensor
51 	            Throttle position sensor
61 	            Oxygen sensor, Cyl. 1-3-5
62 	            Oxygen sensor, Cyl. 2-4-6
71 	            Adaptation, Cyl. 1-3-5 (rich/lean)
72 	            Adaptation, Cyl. 2-4-6 (rich/lean)
81 	            EVAP canister purge valve
91 	            Control module fault (RAM/ROM)