Xantia Bosh Motronic MP5.1.1 Fault codes

[dangerousbrian]

Xantia 1.8 16V 1996 "N" LFY Engine, ECU Bosh MP5.1.1 (0261 204 063) 9624518380
I would like any information of Diagnostic Fault codes or any helpful information to my situation, I have started to experience the yellow fault light flash on "but" not stay on when the engine starts, it can happen when engine is cold or hot, but does not happen all the time, the light does not stay on any more than a few seconds on start up.
I can stops this by just resetting the ECU (disconnecting the battery) & have noticed that when i took it for an Mot the other week that Just the CO Emissions test was failing(CO was all over the show reading up to 0.500% vol , HC & Lambda was ok at the natural idle & fast Idle test, my Max allowed limit for the fast idle test is 0.200 for the CO% Vol & 200PPM vol for HC & Lambda 0.970 .
Luckily I had noticed that the light stayed on for a brief second on start up at the Mot station, I asked for 5 minutes to hopefully fix it & just reset the ecu by disconnecting the battery & the CO level dropped to 0.122% vol on fast idle & 0.093 at natural idle test & so passed the MOT Emissions.
The engine does run smoothly even when the light has flashed on, I do get over 40Mpg on the motorway which I think I really good.
I have a new Cat & have did fix a previous emissions fault, where the air was been sucked in at the manifold end, this was due to new bolts fitted, that were not short enough to compress the manifold springs enough & causing the Lambna sensor to enrich the mixture due to air been sucked in.
Could it be a temp sensor fault?
I have made myself a LED Tester, so I can go onto C3 terminal on the self diagnostic plug(located inside the cars drivers side fuse box), I have the old 30 pin type so a none obd connector, I do not know if I will get any fault codes out as the light does not stay on, but think I can reset it by holding terminal C3 to Earth or 10 seconds I believe & 5 seconds to start the blink codes(fault codes)
Any information about this model of car would be much appreciated, iv'e owned this xantia since 1997 & love it to bits, great car.

[Deanxm]

The best way to go would be to find someone with a lexia and offer them a small bribe to read the code off, i have the codes and what they refer to on the bosch 5.1.1 system though if your interested.

D

[CitroJim]

Hi Brian,

Sadly the ONLY way to read the ECU is with a Citroen Lexia (as Dean says) or with a Citroen ELIT. Nothing else, apart from the eyewateringly expensive Sykes Pickavant ACR4 will really cut the mustard. Lexia or ELIT will give live data so you can see exactly what's going on - especially what the Lambda sensor is up to and that, to be honest, is the most likely cause of your problems.

As Dean says find a soul nearby with a Lexia (there's a thread here listing who and where) and have a proper diagnostic...

[dangerousbrian]

Deanxm, i would be intereseted to know the fault codes and what they refer to on the bosch 5.1.1 system if you would be kind enough to share these, citrojim, i will test the lambda sensor to see if i get an output of 0.45V.thanks

[Deanxm]

i will dig them out tomorrow after work for you but dont forget it could be the heated tip failing or ecu control of the tip instead of just the signal, thats if its not a coolant sensor or map sensor issue, it really is so much quicker to have a lexia session.

Best of luck
D

[CitroJim]

citrojim, i will test the lambda sensor to see if i get an output of 0.45V.thanks

The signal you will see if the lambda sensor is working properly (and the rest of the system) is a cyclic variation in voltage between 0.1V (weak) and 0.8V (rich). You should never see a constant signal from the sensor. If you do, it or something else is not happy. You might see 0.45v if you averaged the reading over a lengthy time period.

[dangerousbrian]

on the subject of Temp Sensors, i would like to know which one to test, looks like i have 3? all next to each other, Blue, Brown, Green in that order from your theromstat, do you measure the resistance changes as the engine warms up?

[CitroJim]

The sensors are as follows:

Green: Engine ECU Coolant Temperature Sensor.
Blue: Over Temperature Warning Lamp
Brown: Bitron Sensor. This one controls cooling fans, A/C authorisation and indirectly drives the temperature gauge.

The green sensor is the only one of interest as far as mixture is concerned. I cannot recall the resistance readings for various temperatures but a Lexia/ELIT session will show if it is working well.

[dangerousbrian]

Deanxm, did you have any luck in digging the fault codes out for a Bosh Motronic MP5.1.1

[Deanxm]

yep, dug them out this evening.

11 End of test
12 start of test
13 air temp sensor
14 coolant temp sensor
15 fuel pump relay
21 throttle position sensor/idle
22/23 ICV
27 vehicle speed sensor
31/32/52 Lambda system control
33 Maf/throttle switch/map sensor
34 carbon canister solonoid valve
35 Throttle position sensor/full load
36 Lambda sensor heater control
41 crank angle sensor
42 inj valve control
43 anti knock control
44 Knock sensor bank 1
45 ignition coil control bank 1
46 turbo pressure valve
47 turbo pressure regulation
51 Lambda sensor
53 battery voltage
54 ecu and anti knock module
55 CO mixture potentiometer
56 coded anti theft
57 ignition coil control bank 2
62 knock sensor bank 2
63 Lambda sensor bank 2
64 mixture control B
65 cylinder sensor
71 Inj 1
72 Inj 2
73 Inj 3
74 Inj 4
75 Inj 5
76 Inj 6
91 Inj control

The above numbers are transfered as blinks from the ecu and are applicable to all mono and early multi point injection manufactured between 1987 - 1997 for all psa vehicles including mono jetronic, jetronic, Mag Marelli G5/G6/8P/ mono motronic, motronic (M1.3/MA 3.0/MP 3.1/MP 3.2/ MP5.1/MP 5.1.1) and Fenix 3B/4.

Hope this helps, i knew i had it around for the xm but didnt know where.

D

[dangerousbrian]

Thanks, for the blink codes,just what i was after, all i need now is the ECU connector pin numbers for all the various sensors, i guess you may have to dig deep to find these out for a Xantia?

[Deanxm]

You 'should' be able to read blink codes

[Deanxm]

Why do you need the ecu plug pinouts? diagnostics can be done , like you say, from the socket under the dash and then the suspect component or its loom checked directl;y.


D

[dangerousbrian]

i would like the ecu plug pin outs to just test the wiring loom out from one end to the other end & would like to put a scope on say the lamba sensor ecu connector end with it all still contected up to look at the varying signal as it's been controlled by the ecu, same for other sensors, i did not think i could look at this if i disconected the sensor.

[dangerousbrian]

Think i may of found a circuit diagram, so edited it into my first post, pins 10 & 28 for oxygen sensor output testing, Thanks deanxm