A5 3.0 TDi Fuel Pump relay

Inexperienced Joined: Jan 19, 2008 Posts: 27

Intermittent fault starting car - diagnosed to (via the below fault code) the fuel pump relay circuit. Can anyone tell me where this relay is, what it looks like / is it the actual relay at fault. Control box underneath bonnet appears dry if this is where it is, if not what is the location of the other relay / fuse boxes. Also fuel pump seems to run on for a while and drain battery with ignition off (is this normal??) - other fault codes then appear but clear once car is running - presumably because battery voltage drops??. When running car runs & drives fine, when it won't start you cannot remove key - Any help much appreciated Thx

PS full log can be posted if required.

1 Fault Found:
5200
Fault Status: 00000001
Fault Priority: 2
- Fuel Pump Relay Control Circuit
P0627 00 [167] - Malfunction or Open Circuit
MIL ON - Not Confirmed - Tested Since Memory Clear
Freeze Frame: Fault Frequency: 1
Mileage: 118612 km
Date: 2014.02.17
Time: 11:47:17

Readiness: 0 0 0 0 1

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Site Moderator Joined: Jan 31, 2003 Posts: 9144

it could easily be your ignition switch

It's the fuel pump relay CONTROL circuit. This is very important. It's the circuit which turns the relay on / off.

fuel pump shouldn't run with the ignition off. If it still runs, it thinks your ignition is still on.

You could try some spray grease in to the slot for key

Inexperienced Joined: Jan 19, 2008 Posts: 27

Cheers Mike, I have cleaned the fob sides around the small cut outs with some Audi universal spray lube, I have sprayed some WD 40 contact cleaner down the ignition where the key fob goes. Sometime I have noticed the key sticking when removing it so maybe you have hit on something (control Circuit fault) - the key fob does feel smoother now when sliding in and out. I have looked around the internet and a relay fault seems to be code J17 so the relay could be ok.

Should the pump immediately turn itself off when the key is removed or does it run on for a bit?

Also I have noticed that if I don't push the fob in completely (ie only push to position one) pause then push it in the fault seems to happen, also I have noticed that if the key fob is pushed to position 1 the coil / glow plug light flashes, it goes out once the fob is pushed all the way and the engine starts - is this normal?

Thx once again.

Site Moderator Joined: Jan 31, 2003 Posts: 9144

I'll check on my own car - can't say I've noticed the pump run after shut down.

I take it you don't have push button start

Inexperienced Joined: Jan 19, 2008 Posts: 27

The car is started by inserting the fob and pressing it, to stop the car you press the fob again and pull it out, sometimes however it gets stuck and won't allow you to remove it. I have to keep trying to start and stop the car a few times before it lets me remove the fob. During this time the fuel pump is running and drains the battery, this is when the other faults warning appear relating to low voltage but go once the car starts.

Its not the old style keyed ignition barrel if that what you mean, but dont have a separate start button its all done via inserting the fob. Cheers

Site Moderator Joined: Jan 31, 2003 Posts: 9144

Fully aware of the key in the A5 - I've got the same car as you.

When you push the key in to the first position, you get ignition only. No lights on dash and no fuel prime.

Push it in to the 2nd position without touching the brake (mines an auto) and you get all the dash lights come on and the pump will run for about 2-3 seconds.

I don't get the coil flashing though.

When you switch off, there is no pump noise

Inexperienced Joined: Jan 19, 2008 Posts: 27

Ok Thanks Mike, I will monitor it again and see what happens, I think you may be right some sort of ignition fault???? I will post back if there are any updates.

Thanks once again.