120d - DTC light came on and engine lost power.

120d - DTC light came on and engine lost power.

Author
Discussion

MitchT

Original Poster:

15,788 posts

208 months

Saturday 22nd July 2017
quotequote all
Just completed a 20 mile journey on the motorway. About two thirds of the way a light started flashing on the dashboard and the car started slowing down. The light and the power loss seemed to come and go intermittently. When we arrived at our destination I googled and the result I found suggested that it's the DTC light and that if I turn the DTC off it won't bother me again, so I can at least get home. Any thoughts?

ETA: Car is an early 2005 120d (first generation) with about 90k on the clock. The google result suggested a faulty ABS sensor or a ring on the drive shaft that can become corroded. Not sure how either would cause power loss.

Edited by MitchT on Saturday 22 July 16:39

helix402

7,832 posts

181 months

Saturday 22nd July 2017
quotequote all
The fault will be rust between a rear abs reluctor ring and driveshaft. Look on eBay, buy a sensor and ring kit. R&r driveshaft, replace ring and sensor. New hub nut also needed.
Be aware that shafts sometimes also seize into the hub. To diagnose observe live data wheel speeds and see which one jumps around. No fault code will usually be stored.

Thermobaric

725 posts

119 months

Saturday 22nd July 2017
quotequote all
Yeah, will be reluctor ring, driveshaft issue.

One press on the DTC button will turn that off. You might be OK with just that. If you still have issues with power you can fully turn off DSC by holding down the DTC button for 5 seconds.

MitchT

Original Poster:

15,788 posts

208 months

Saturday 22nd July 2017
quotequote all
Cheers both - main issue is just making sure we can get home - we have repair options available on Monday. We have a non-motorway route avilable as a safer option so just want to be sure we can actually make it!

MitchT

Original Poster:

15,788 posts

208 months

Saturday 22nd July 2017
quotequote all
Drove home. Avoided the motorway just in case. No issues so I couldn't try the DTP button! Why can you never replicate a fault when you actually want to?

randers

13 posts

86 months

Monday 24th July 2017
quotequote all
I've had this recently on my wife's 120d, changed the reluctor rings on the rear and the ABS sensors, no problems since.

Thermobaric

725 posts

119 months

Monday 24th July 2017
quotequote all
So cheeky this is such a widespread issue across many models and not covered under extended warranty.

MitchT

Original Poster:

15,788 posts

208 months

Wednesday 9th August 2017
quotequote all
Haven't had this fixed yet as the problem hasn't reappeared since, though today the power was cutting sharply at both constant speeds and under acceleration. The sensation was exactly like that of the t/c kicking in, but nothing lit up on the dashboard. I turned the DTC off and it didn't happen again but we were nearly home so I'm not sure if turning the DTC off had stopped it or if it simply hadn't happened again. Same issue?

SebringMan

1,773 posts

185 months

Wednesday 9th August 2017
quotequote all
Where in the country are you? If in Warwickshire I am happy to scan the car using INPA smile.

MitchT

Original Poster:

15,788 posts

208 months

Wednesday 9th August 2017
quotequote all
SebringMan said:
Where in the country are you? If in Warwickshire I am happy to scan the car using INPA smile.
West Yorkshire, but thanks for the offer. Fortunately I know someone who could scan it if necessary. As it happens it needs a new EGR valve too (separate existing issue) so we'll maybe get the latest issue looked at when we get that done.