Hi All,

 

I’ve been having an issue with my Mk5 1.6 TDI diesel (2010 plate, approx. 83000 miles) for a few weeks now, and several garages have been unable to solve it. I bought the car from a national used car chain 7 months ago, but unfortunately it’s now out of warranty.

 

I got a flashing engine management light on my dash about 3 weeks ago, which was followed by a loss of power to the engine - it could still run and cruise at 30-40mph, but accelerating past ~40mph, and accelerating away from lights was noticeably slower.

 

I took it to a local garage who reset the light, but it came back the next day so they ran a diagnostic which said the fuel rail pressure was low. They rinsed the fuel lines and cleaned the filter (can’t remember exactly which one), then took it for a test drive and said it was running fine, but the light came back again the next day at the exact same spot on my commute. I booked it into a VW dealership’s garage for yesterday, and they said that there was a battery defect and they were confident that changing the battery would sort it.

 

I took it to a different local garage to get the battery changed today, and they said they couldn’t find any faults with it, and that even changing the battery didn’t seem necessary. I took it for a test run this evening with the new battery fitted, and the light came on at exactly the same point in my journey. This occurs about 15 minutes into the drive, after going from 30-40-60-30-60mph along an A road - the light comes on at the end of a ~0.5 mile stretch of the A road with a 60mph limit.

 

Apologies for the length of the post, but any tips would be much appreciated! I’ve tried tightening the fuel cap but that made no difference. I’m also supposed to be moving 3 hours away next week and currently don’t have a car to do it with!

 

Thanks in advance,

 

Matt

I’m no expert on VW Diesels, so this is just a bit of general engine management/ diesel knowledge I have.
 

The loss of power is the engine management system going into ‘limp home’ mode in response to a detected fault with the system and it is what it says, a chance to get it home, or to a garage.

 

If the 1st garage has seen an error of fuel rail pressure then that at least gives  you(and them)something to go on.If they cleared the error code another check should see if it’s the same one that had come back when it failed again.Unfortunately Engine Management systems are very complicated and you need the proper diagnostic equipment to help get to the bottom of the problem.It could be something as simple as a pressure sensor or a regulator, so hopefully not an expensive fix.

 

You say that they rinsed the fuel lines and filter,? With diesels they need to be meticulously maintained with regular Fuel filter changes, so it’s probably best to renew the diesel fuel filter as a matter of course anyway, especially if you have no evidence of when it was last changed.