Hi, a little help diagnosing this please.

2010 Mini Cooper hatch

While driving the car will start to sputter/hesitate then the ABS warning light comes on and the sputtering/hesitation stops.

I tested the ABS (having someone stand outside the car and video while I slam on the brakes... yes, I'm hi-tech like that). Both front wheels lock up upon hard braking.

It seems pretty unlikely that both sensors would go bad at the same time? and the hesitation/sputtering doesn't make sense in connection.

What do experts think? TIA

 

anyone? Argh, I hate to pay the price that the dealer will want to diagnose this.

 

I recently saw a post on facebook (can't remember the group) describing the exact same problem. One person stated that it was due to a bad ABS sensor. The bad sensor was causing the engine to reduce power. SOme older Chevy pickup trucks have the same issue.

 

It seems improbable that both sensors would go bad at the same time. I suppose it could be a safety feature? I mean, it could be dangerous to have one front wheel anti-lock and the other not... sounds like a recipe for spin outs.

So my hypothesis will be: one sensor goes bad and the computer shuts down both... and the bad sensor draws an overload of power from the computer when it shorts out. Yeah? LOL. Well, the sensors are available for $25 on the web so I think I'll buy two, replace them both and see what happens.

 

Could the issue be caused by a bad / burnt out ABS fuse? That could be an explanation of why both are down?

 

Sorry, I should've mentioned that in my OP as it was my first thought, too.

Fuse is 25amp. Visual inspection looked good and later confirmed with my voltmeter that the fuse is indeed passing current.

 

When there is an ABS failure code, the ABS will be disabled, and braking will revert to "normal" braking, no ABS at all. The sputtering you describe could be the ABS failing somehow, then it goes away because from that point on, ABS is disabled. You will need to read ABS codes, then go from there.

 

Thanks, renchjeep. You're confirming my hypothesis at least. ;-)

My code reader won't read mini specific OBD codes. It reads BMW codes, and if I select that option it shows P1777. But, I have no idea if Minis use the same OBD codes as biemers. I suppose I could take a trip to Aamco and get them to read codes for me... but at this point I'm kind of committed to just swapping out the sensors.

 

I replaced both front ABS sensors today. Super easy job, took me about an hour to do both.

After a short 5-10 mile test drive, it seems to be a happy little car with no more symptoms as described above.

My OBD reader won't clear the check engine light, so I'll take it to an Aamco on Monday and get them to do it for me. I'll update this thread later in the week after the car has some more miles and let everyone know whether the symptoms show back up (that way other people that find the same symptoms through a google search will have an answer).

 

Update:

I didn't need the trip to Aamco to clear the check engine light, it came off on its own after another 5-10 miles of driving.

At this point, I'm declaring the car fixed.

Summary: the car would hesitate and sputter while driving; then the ABS warning light would come on and the hesitation and sputtering would stop -- but the ABS system was not working (confirmed by slamming on the brakes and visibly watching the front wheels lock up). The check engine light didn't come on immediately, but it did after several miles. I replaced both front ABS sensors and now all the symptoms are gone and the check engine light turned off by itself.

Hope this helps someone else in the future.