X5 3.0D Replace ECU
 

Hi,

I have already raised this in another thread but in relation to another issue so appologies if you have read this already.

Just before taking my X5 into an indy last week to have an injector replaced and a repair to the A/C (stone damage) I had two errors flash up. <Fuel Injection System> <Trans Fail Safe>. I though they might be related to the injector, mentioned it to the service manager who said they would check it out.

Picked up the car on Friday, went to start it same errors. Diagnosic identified low voltage from ECU, suspected a low battery. I changed the battery on Saturday (5 1/2 years old) with a quaility replacement expecting all to be well.

Sunday the error codes appeared again.

Took the car back to the indy today. Put back on diagnostic kit. First thought it was the cam sensor relay, however on further investigation (they bypassed the relay) the fault was traced to the ECU. 12 volts going in 6 volts coming out to transmission and fuel injection pins. No error codes as it is internal. (I'm sure there is a more technical explanation but that was the gist of it)

They say I will have to replace the ECU which is about £1200, on top of the £1100 I spent last week.

Has anyone had a similar experienece and does this sound reasonable? I do trust them as they are a quality outfit but having searched around I would rather it was a sensor or bad earth connection! I dont want to spend all that money and then find it is something else costing more money.

Also if it is the ECU would you consider a repair rather than an new one?

Any advice would be really helpful.

i would want to double check that, as it is my understanding based on other cars (not BMW) that the voltage coming out of the ECU to sensors etc is supposed to be 5v , so 6 would probably be ok

so before you go spending any money double check it

Can you give us some more feedback?As Big wave said ,ECU sends out 5V !
What work was done on your car that you paid £1100 for?Did you pay all that for an injector replacement and A/c fix?Also .apart from the errors trans fail and Fuel inj,how does the car perform?Did someone try to remap your car?
If it is in fact ECU fault,before you buy a new one ,you should get it flashed back or updated with software,,and then see if you still get errors.

Thanks that is good advice I will get it tested somewhere else.

Yes I did pay all that for injector replacement and a new evaporator. The injector was £299, the evaporator was £320. Plus Labour and VAT = £1100. Would have been £1500+ from a main dealer.

The car perfoms well with the new injector (and before actually). There has been no attemp to re-map, although I have considred it. Car has run faultlessly for the 5 and a half years I have owned it from new. I have just completed a 125 mile trip this morning and it ran great. Switched off and tried to re-start all the errors again. The probelm does seem to be connected with the engine being hot.

You are right ,main dealer would have been more expensive,but a good dealer wouldnt hand you the car back with the same error codes it went in with!I say this because you had the injector replaced and the error code is still there and without or with new injector,engine performance is flawless,which suggests the old injector was still fine but yet they still made a decision to replace it.How did they diagnose a fault in that specific injector?At the dealer we cant charge clients for replacing parts that were not faulty in the first place and obviously didnt resolve the issue.

Why do you say the problem seems to be connected to engine being hot?You car performs fine,right!Its just the error codes.Do they error codes only come up when the engine is warmed up?In any case ,the best thing in my opinion ,would be to have the car properly diagnosed by a dealer (for example,BmwGloucester only charge 1/4 hour for Diag),maybe they will register some other error codes and reflash +update your ecu sotware.

Powers1

Main dealer did initially diagnosed the faulty injector during a service. I forgot to mention that before it was changed the car was missing on idle and smoky on start up. It ran OK and would clear sometimes but there was a fault for about 6 months before I got it fixed.

I asked the indy specifically to change that injector. They are a Bosch service centre not some back street operation. They did confirm that that they had tested all the injectors and one was way out but the others were well in spec.

The error codes it now seems were not related to the injector just a coincedence that they started just before I took it in to be fixed. But I had been running with the dodgy injector for some months before the errors came up.

The error codes do only seem to happen after the car has been run. This morning it started up just fine, but tried to restart after 125 miles and errors came up on screen.

I think you may be right about a main delaer diagnosis, better to spend £50 rather than a £1200 and still find the errors.

Thanks for your help.

Now you gave us more further feedback ,the injector replacement makes more sense.
After the engine is warmed up and the errors are registered ,is there any decrease in performance,or is it the same?
It maybe and I hope its something simple as a fuel pressure sensor,coolant sensor or boost sensor malfunction.
I understand that your "indy" is a reputable workshop,but what myself and Bigwave are also trying to say ,is for you to get a second professsional opinion and NOT to go and have the ECU replaced until you are 100% sure that thats the problem.
I hope that at the dealer they will be able to diagnose the specific location of the error code.Please report back :thumbup:

Powers1

Sorry for the incomplete info earlier.

If the errors come up when I switch on the motor will crank but will not start. So far I have been able to clear them by switching off, waiting until they disapear and then trying again. I sometimes have to do this a few times to clear it.

The errors have not come up while driving (than heavens!)

Believe me I hope it is a sensor as well! I would hate to replace the ECU to find that there was still a problem!

Thanks for your continued interest and advice.

From what you are saying it could be just the fuel pressure sensor on the rail.This is as a common fault on the 3.0D as the FSR is in most E53-X5s...
Good luck with the dealer diagnostics.:thumbup: