A friends A4 with a handful of issues

MikeSel^

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Hello All

One of my friends picked up an A4, on my recommendation of the Audi brand. She's had nothing but problems with it, which are as follows:

So basically, 2/3 times it starts ok, but when it doesn’t, it ticks over but doesn’t ‘fire up’ and a warning light comes up on the dash board. The most frequent icon is Brakes but others have come up. The garage have checked the various areas it has warned about and there are no issues so they believe it is an issue with the dashboard. They did get it sent off to a place that tests dashboards but the area that they wanted testing specifically, they couldn’t do for some reason, so nothing actually got solved, but the problem did sort for a while because he reckoned that it was a kind of reset. This lasted only a few weeks before it started happening again.

Often if you wait a while, take the key out, unlock and lock the car, the car will randomly start again ok.

Sometimes, the warning lights don’t come on but the car struggles to fire up. My brother in law says that it feels like there is a hole in the fuel pipe? Sometimes but not always, the car smells quite fuelley.

I get the feeling these are two separate issues. What do you think?
 
Ooops :D

Sorry
  • Date of first registration: November 2006
  • Year of manufacture: 2006
  • Cylinder capacity (cc): 1986 cc
  • CO₂Emissions: 179 g/km
  • Fuel type: DIESEL
 
VCDS diagnostic to see if there are any fault codes stored. If it's had warning lights on there should be some.


There's a few common faults that cause start up issues.
Fuel pump relay. IIRC its relay 167 located behind the interior fuse box. Turn ignition on & listen for the fuel pump (it's under the back seat).
Cam or Crank sensor failure.
Coolant temp sensor failure causing incorrect fueling.
Rain water collecting in the Plenum chamber, & ingressing into the ECU, & relays under the ECU housing.
Incorrect timing.

Have to say dashboard failure is rare on Audi A4 B6's.
If there was a hole in a fuel line you'd see signs of leakage for sure, more likely your smelling unburnt fuel from the engine not firing up.
 
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The brake light on the dashboard could be a faulty sensor, mine sometimes comes on but I know the brakes are fine as discs and pads were replaced not too long ago.
 
Brake light switch is another common failure, which can cause warning lights.
 
As indicated above there are many possible causes of problem starting. Just eliminating a few diesel basics - the car is 11 years old, when was the fuel filter last changed? Is the problem restricted to the first cold start of the day in which case the glow plugs might be getting old? Faulty glow plugs don't tend to be so evident on a start when the engine is still fairly hot from having run shortly before.

It sounds as if the garage has just "walked away" from the problem and so I am assuming it is a high street "non specialist" place. If so, I would take the car to either a local Main dealer or independent VAG specialist so that they can scan with specific VAG software and they will have better, specific VAG experience.
 
What condition is the battery in? Spurious electrical problems can often be caused by dying batteries and the brake warning light ((!)) will often come on when cranking with a battery on its way out.

Frank