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View Full Version : Question Golf VI Hatchback (5K1) 1.6 TDI 105 hp Diesel CAYC Fuel pressure regulator fault?



Andy Bell
13-12-2023, 06:00 PM
Hi all

Yesterday my Golf suddenly went into limp mode when I was doing about 50mph and accelerating up to 60mph. The orange coil warning light started flashing. After restarting the engine, the light went out but soon came on again with the car losing power and going into limp mode the moment the engine was under any strain.

The AA came out and checked the fuel pressure sensor (tried a new one, made no difference), the fuel (was ok) and couldn't tie down the fault and so towed me home. The AA did get diagnostic messages on their computer, which made them check the fuel system.

Today, the problem is occurring frequently - as soon as the engine is under strain, such as going up any incline at 30mph, it happens. Revving the engine to 2500 rpm when stationary does not cause the problem.

A mechanic I often use came out today and confirmed that the fuel pressure regulator diagnostic error was on the computer - he took the car for a run with his computer connected and replicated the fault.

He checked all the injectors for issues and the fuel lines etc. He said the HPFP was ok and there was steady pressure from the in-tank pump. The fuel filter had been changed in September but I don't know if he checked it.

His suggestion is to replace the fuel pressure regulator, but he couldn't guarantee that would fix it. These things aren't cheap (approx £400 + VAT from VW) so I'm uncertain if this is the right move. The car is in otherwise good condition, having done 107,000 miles and has never had a serious issue before.

The mechanic is going to see if he can find a third party component that is good quality but cheaper.

My questions are:

Is this the most likely cause of the problem?

Is there anything else he should check before replacing the part to see if it helps?

Thanks everyone,

Andy

Andy Bell
21-12-2023, 06:22 PM
I now have the fault codes:

P003700
P229A00

An independent garage gave me these and recommended going to a main VW dealer as they didn't have the equipment to determine which part(s) were causing these faults.

My nearest VW dealer has quoted me £100 to do the diagnostics.

Does anyone know what these codes indicate?

Crasher
22-12-2023, 10:40 AM
20642 (P0037) - Oxygen (Lambda) Sensor B1 S2: Heating Circuit - Short to Ground. MIL ON


10116 (P0087) - Fuel Rail/System Pressure - Too Low


It is likely you have two faults, the lambda sensor and the high pressure fuel pump, these usually fail after a new filter has been fitted and the system has not been bled before starting the engine.

Andy Bell
22-12-2023, 11:15 AM
Thank you for the response. It doesn't sound good - I suspect the repair cost would far exceed the worth of the car.

The fuel filter was changed on 19th September and the fault first occurred on 12th December after I had done approximately 3,000 miles. Would that rule out the fuel filter change as the culprit, or can the failure occur that slowly after the change?

Many thanks,

Andy

Crasher
22-12-2023, 11:42 AM
Difficult to say, if there were no traces of ally particles on the filter AND the system was fully bled before starting then I would say it is just wear and tear. If the system wasn't bled then possibly the reason.

Andy Bell
22-12-2023, 12:05 PM
Thanks Crasher

The same mechanic changed it in the previous full service, so I think he knows what he's doing, but people make mistakes. I think he would have told me if he had spotted issues with the old filter or particles in it. In any case, I can't wind back time and change anything...

My local VW main dealer are going to look at it and give me a quote for repairs next Wednesday. I told them to have a defibrillator at the ready lol

Andy

Crasher
22-12-2023, 05:02 PM
Buying the part exchange from Bosch is a LOT less than genuine.