[Sarlech]

Hi guys

I went to test drive a 640d a few days ago - it had been at the showroom for approx. 2 weeks, I took it for a test drive (after driving approx 200m down the road a warning light displayed a problem with the drivetrain (can't remember the exact wording)) and went into limp mode

The guy then said most diesels do this at his garage due to being constantly stop-started when moving them around, and would just require a flush due to the DPF

Is this correct or is it likely to be something more serious?

Thanks in advance

[bvanlieu]

Like many M57 enthusiasts in the US, mine has thrown a few codes frequently: about ever 6 months. Never has it gone into limp mode. I also had a CBU service done after 70K so know how they can run rough but still run with that ailment.

This sounds like poppycock to me.

- b

[Maynard]

Excellent leverage to get them to throw in a complimentary warranty extension?

[floydarogers]

There may be some confusion in what is called "limp mode".

There are two levels of Service Engine Soon (also called Check Engine Light): yellow light indicating a need for repair to correct an engine problem causing excess pollution or other minor problem. Red to indicate a more serious problem with the engine (usually accompanied with rough running/missing.)

The 2nd condition often is accompanied with a "limp" mode, which reduces power and can force you to stop the car and get a tow.

Modern BMW diesels with the BlueTec pollution control hardware often (!!!) set the yellow SES because the system detected that more NOx than spec was being emitted. This check occurs every DPF regeneration cycle (about every tankful/500 miles). If it goes out at the next regeneration, (has happened to my 335d 5-6 times), you're good to go (although be warned eventually it will stay on - these systems are so fragile.)

The salesman is full of it. SES is not supposed to happen in the normal operation of the vehicle. There is no way the salesman could tell you without attaching an OBD reader to the car, that the problem could be ignored.

[Sarlech]

Originally Posted by floydarogers

There may be some confusion in what is called "limp mode".

There are two levels of Service Engine Soon (also called Check Engine Light): yellow light indicating a need for repair to correct an engine problem causing excess pollution or other minor problem. Red to indicate a more serious problem with the engine (usually accompanied with rough running/missing.)

The 2nd condition often is accompanied with a "limp" mode, which reduces power and can force you to stop the car and get a tow.

Modern BMW diesels with the BlueTec pollution control hardware often (!!!) set the yellow SES because the system detected that more NOx than spec was being emitted. This check occurs every DPF regeneration cycle (about every tankful/500 miles). If it goes out at the next regeneration, (has happened to my 335d 5-6 times), you're good to go (although be warned eventually it will stay on - these systems are so fragile.)

The salesman is full of it. SES is not supposed to happen in the normal operation of the vehicle. There is no way the salesman could tell you without attaching an OBD reader to the car, that the problem could be ignored.

Originally Posted by floydarogers

There may be some confusion in what is called "limp mode".

There are two levels of Service Engine Soon (also called Check Engine Light): yellow light indicating a need for repair to correct an engine problem causing excess pollution or other minor problem. Red to indicate a more serious problem with the engine (usually accompanied with rough running/missing.)

The 2nd condition often is accompanied with a "limp" mode, which reduces power and can force you to stop the car and get a tow.

Modern BMW diesels with the BlueTec pollution control hardware often (!!!) set the yellow SES because the system detected that more NOx than spec was being emitted. This check occurs every DPF regeneration cycle (about every tankful/500 miles). If it goes out at the next regeneration, (has happened to my 335d 5-6 times), you're good to go (although be warned eventually it will stay on - these systems are so fragile.)

The salesman is full of it. SES is not supposed to happen in the normal operation of the vehicle. There is no way the salesman could tell you without attaching an OBD reader to the car, that the problem could be ignored.

Thanks for information on this - much appreciated

[NormanConquest]

Diesel cars are only good if you do 30 mile trips on highway with no traffic daily

[Sarlech]

I do approx 15-17k a year; 90% of which are motorway miles; a petrol wouldn't be any good to me

[NormanConquest]

Originally Posted by Sarlech

I do approx 15-17k a year; 90% of which are motorway miles; a petrol wouldn't be any good to me

Then you should be fine since that will allow for a regen. Some people buy diesel and do short distance city driving which prevent their car from having enough time to perform a regen which results in the most common diesel breakdown occurring now. To avoid that you need to buy a car with a Manuel regen mode that allows you to sit in a parking lot for 30 minutes while it cleans the system.