How to read the fault codes??

All aspects of tuning,modification and repairs to the BX 16valve.
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Joined:Sat Aug 18, 2012 1:54 pm
How to read the fault codes??

Post by Jayridium » Fri Nov 30, 2012 9:32 pm

I have found numerous pages explaining what the fault codes are for each component, but I simply cannot find how we put our cars into diagnostics modes so I can read the fault codes on my h reg valver?

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Joined:Sat Aug 18, 2012 1:54 pm

Post by Jayridium » Thu Dec 06, 2012 9:48 pm

Credit to barryg on ausiefrogs for the following helpful insight into how to extract the codes from the motronic 1.3 ecu
It's pretty easy to do once you get the gist of what needs to be done.

Locate the 2 pin diagnostic connector. On the BX TZi it's on the driver's side near the sphere. Stick a wire into pin 1. Pin 1 is as shown below:

| x x | Looking at the pins, keep notch to the top, pin 1 is left hand pin.
^ pin 1

Using the wire attached to pin 1 as shown above, do the following:

1/ Turn ignition on (but don't start the engine)

2/ Ground pin 1 using the attached wire for 3 seconds. This means touch the wire from pin 1 to some convenient chassis ground point for three seconds, then disconnect from ground. One could connect a switch (one side pin 1, other side chassis ground) for this purpose, but I found just touching the wire on something chassis ground worked fine.

3/ You should see the code 12 flashed on the check engine light

4/ wait until the check engine light is lit continuously. This is about 3 seconds after the code has flashed.

5/ ground the wire from pin 1 again for 3 seconds.

6/ The next stored code will be flashed, or the code 11 is flashed indicating end of stored codes.

7/ if not code 11 repeat steps 4-6.

8/ Once code 11 has been flashed the ECU can be cleared of stored codes by grounding the wire from pin 1 for 10+ seconds when the check engine light is lit continuously.

9/ For an ECU with no stored codes this process will yield code 12 followed by code 11.

10/ Not all error conditions will result in the check engine light coming on whilst driving, but the codes will be stored. Thus, this may be a worthwhile thing to do every so often just to make sure all is well.

and what the codes mean once we have them can be made sense of by using this article from
Fault codes for Bosch Motronic 1.3 Injection
405 MY16 up to MY93.
(1.9 litre engine) XU9J4
Code Description
13 Inlet air thermistor
14 Coolant thermistor
15 Fuel pump relay
21 Throttle switch idle function
22 Idle regulation valve
31 Mixture regulation auto-adaptation
32 Mixture regulation auto-adaptation
33 Air flow sensor
34 Canister purge valve
35 Throttle switch full load function
41 Engine speed sensor
42 Injector control
43 Anti-knock function
44 Knock detector
51 Oxygen sensor
52 Mixture regulation
53 Battery voltage
54 Control Unit
55 Mixture adjustment potentiometer

I have still to try it myself but I will report back with my results

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Joined:Sat Aug 18, 2012 1:54 pm

Post by Jayridium » Sun Dec 16, 2012 1:44 pm

just a quick follow up I tried the procedure above got my fault codes and have ordered the appropriate parts, I did however find the ascii art drawing of the plug a little misleading. There is an outer shroud which has multiple notches in it, the ascii art is drawing only the inner shroud and seems to ahve the highs and lows inverted...

ie instead of:
| x x |

the Diagram should look like:
| x x |

as always a picture is worth a thousand words, so see the following picture, bearing in mind it is the left pin you need to work with.


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