Page 19.16 Fault code table (Citroen and Peugeot)
11 End of diagnosis
12 Initiation of diagnosis
22 Stepper motor
31x Lambda control
42 Injector or fuel pump control
52 Lambda control
53x Battery voltage
x Faults that typically will cause the ECM to enter LOS (limited
operating strategy) and use a default value in place of the sensor.
To obtain fault codes short the green lead side of the Fault Code
Reader (FCR) multi-plug to earth for 4 seconds with the ignition on
while an assistant watches the fault lamp on the dashboard (or use two
long lengths of cable). To clear the fault codes short for 10 seconds,
or remove the ECM multiplug. The FCR is situated by the o/s headlamp.
My 1994 Citroen AX had a running problem. The Electronic Control Module
(ECM) was unable to read the Coolant Temperature Sensor (CTS) giving
fault code 14. The CTS was replaced to no avail. The replacement died
two years later. The sensor should read around 4k ohm at 10C, 2.2 -
2.8 k ohm at 20 C. It will go open circuit if the thermistor is dead.
To change the CTS place a 19mm socket over the sensor before partially
inserting a 1/2" drive. Placing the socket over the sensor with the
drive fully inserted will break the sensor from its mounting.
Fault code 14 makes the ECM substitute a default value which makes the
engine run badly. The problem was a poor connection on pin 25 of the
multi-plug (P19.14 - the lead in the illustration is on the wrong end
of the plug). The middle row starts at pin 20 from the lead end. (Check
for continuity between pin 25 and the CTS first.) Removing and
replacing the plug would cure the problem and remove the fault code
temporarily. I eventually cured the problem by cutting the lead to pin
25 and soldering a permanent connection to the male pin on the ECM. I
also had to connect one side of the CTS to the earth point on the
suspension strut upper mounting, as both the earth and 5V signals were
intermittent due to corrosion on the ECM multiplug.
If the Throttle Potentiometer (TPS) wears out (mine did at 50,000), a
replacement is around 300 quid (Citroen parts are around 25% cheaper in
France). The manufacturing cost is probably no more than a pound. I
wrote to the Consumers Association but they weren't interested. If
you're buying second hand check the fault codes first. Take the vehicle
for a run first in case the owner has cleared the fault codes from the
memory of the ECM!
Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here.
All logos and trade names are the property of their respective owners.