52 Plate 1.4 Hdi 8V not starting

Hi,

Hoping someone can help shed some light on the problem I'm having with my C3.

The engine was changed for a second hand unit about 6 months ago and the car started and run ok at first. Then after about a month while driving the car went into limp mode and wouln't rev over 2000, however had no lights on the dash. Got home biut since then will not start.

Under diagnostics have been given error code P1641, spoke to local Citroen dealer who said 99% of the time a faulty ECU is the cause of this code. The ECU was sent off to a company who said was faulty but fixed it, however problem still present. Sent the ECU back off same company who had someone else check it who advised would need a reconditioned one, so at further expensive exchanged it for a reconditioned ECU that they said were able to program without the car. Car still refuses to start.

In addition to this the wiring loom under the airbox and fuse box in engine bay have both been replaced. Also checked the fuel presure and that seems ok.

Any ideas what to check next?

stepaz80 wrote: so at further expensive exchanged it for a reconditioned ECU that they said were able to program without the car. Car still refuses to start.

I would double check the Engine ECU is matched to the BSI, because if they are not then it won't start. This is very likely if reprogramming (immo off) didn't work on the ECU programming. I have never had the chance to play with an immo off ECU because the usual path is to just change the BSI, keyfob and ECU as a matched set from a scrapped car.

Use the lexia tool from here (amazon) or the same thing from here (ebay) and check for faults, matched ECU and immobiliser faults.

Read-up about what lexia is here.

Other faults can be a fuel/injector fault, but if you had a replacement engine were the injectors recondtioned/replaced or a low mileage engine used? Check for injector failure with a Leak Off test (info here).

Or use Lexia to gather all the fault codes and start from there.



This is a good (untouched) ECU matched correctly to the BSI and immobiliser (immo) OK.

P1641, spoke to local Citroen dealer who said 99% of the time a faulty ECU is the cause of this code.

1% says injectors or loom. Did the 'new' engine keep the loom or injectors from the original engine?

Hi, if I was to get a bsi, ecu and key from another car would that work?

Thanks for all your help

stepaz80 wrote:Hi, if I was to get a bsi, ecu and key from another car would that work?

Thanks for all your help

You can swap the BSI with its engine ECU and the car Key into another C3 and it will work.

You will need to match same (or very similar, eg 2002-2005 won't fit 2006) year BSI and match the correct Engine ECU (from 2 types for diesels).

If any of the equipment is different then you will need to reprogram the BSI using lexia to enable or disable the true features of the car.

You may need to update the software in the BSI, but that is also done using lexia.

If your fault is not with the engine ECU or BSI or KEY, then swapping them won't fix the car.