I have an A4 avant 2.5 v6 auto on an 04 plate.The problem is that sometimes it just won't start. Turn the key and nothing.This seems to happen after the car has got nice and warm and if I leave it for about an hour it normally starts fine. After short trips of around 6 miles it seems to be ok too.Anything you can advise, is it something as simple as an over heating relay or worse?
Country: United KingdomMake: AudiModel: A4 Quattro AvantYear: 2004Engine: 2.5 v6 diesel
Leaving it for half hour to an hour seems to work.
Have looked at the fuses, but can't find any relays. the owners manual doesn't mention them :(
Hello If the car's not cranking then first check that the main battery cables are on tight and the terminals are clean and bright. Do the same for the engine / gearbox earth strap. Then follow the main positive lead back to the engine and down to the starter motor, and check the connection at this end as well.
There should also be a small wire to the motor which should have 12V when you're turning the ignition switch to crank. If the 12V isn't there, check back along this wire for damage to the insulation or corroded connections
This 12V feed comes directly from the ignition switch so this may be faulty and need replacing
Check the resistance of the main positive lead that runs down to the motor as anything more than a few ohms and it should be replaced
Don't forget to try a jump start from another car / battery as its possible the battery is poor, if you have a voltmeter a healthy battery should read 12.7+V
also try substituting the battery for another as I've known a very flat battery to drag down the system voltage too far even with jump cables If this is all OK then its possible the car needs a new starter motor
All above looks to be fine.Used the car to day and just got back on the back of a recove5ry lorry.Again the car wouldn't turn over. Left it to cool down for an hour and gave it a try. Started fine.The only problem then was I couldn't move the gear shift out of park. The foot brake indicator was illuminated and wouldn't go out when I depressed the peddle.I had to turn the engine off to select Neutral. It then wouldn’t start.While waiting for the recovery bods, I checked all the fuses, all fine, looked around the engine bay for obvious signs of something wrong.I turned the key to the run position, the one just before start, and didn’t get the “use brake while selecting gear” or whatever it is and the gear selector showed all the gears lit but not the footbrake light. I moved the selector through the gears and the tiptronic, it all registered on the dash and then dropped it back into park. Did this a couple of times and then the brake light lit. I was then able to start the engine without fuss. I was even able to select drive and reverse, even managed to move it about 20 ft in both directions, then I couldn’t move the selector out of neutral.This also happened when the recovery lorry arrived. Could start the engine, but not take it out of park.Ideas?
Hellothanks for the extra information, in that case it sounds like an issue with the brake inhibitor circuitI'd 1st check the brake pedal switch at the top of the pedal in the footwell, some cars have more than one switch so while brake lights may work fine the inhibitor switch may not so check them all with a meter
Thanks, XXXXX XXXXX a look in the morning.I'll let you know how I get on.
No problem just get back to me on this post
Latest update, warmed the car up this morning for about an hour so it was good and hot, guess what... the damn thing didn't bat an eyelid. Turned it off and on again a few timers, even engaged drive and reverse a few times moving up and down the drive. Still no issues, everything looked to be working so stuck it into neutral and left it there for about half hour.When I came back, low and behold the footbrake light wasn't lit and I couldn't engage drive or reverse again.I'm slowly noticing additional things that I'd seen before but not registered.When the car fails, there is no highlight in P or N.The switches for the brake pedal seem to be ok by the way.
Hellothanks for the extra information this is sounding more like an issue with the gear selection sensor just under the gear leverSo I doubt that the switch itself has failed but they are prone to getting clogged up with dust and dirt from the cabin so its worth removing the centre console trim to access the switch / sensor and five it and its connector plug a good clean with switch cleaner ( Not WD40) intermittent connections can be subject to temperature as things can push apart as they expand as they warm up
Hi Matt.Sorry for the long delay in getting back to you, but I've had no joy.Ended up taking the car to Audi and it looks like it's the gearbox controller, £1500 if I get them to deal with at least a 10 day wait for the parts.Looks like I'm stuffed unless I can find someone in the Norwich area that can do the work for less :(
Hello KenI'd locate the services of an Audi specialist / independent as you'll get Audi knowledge without the dealer pricetry http://www.svaspecialistofnorwich.co.uk/orhttp://www.audinorwich.com/servicing_prices.htmor http://www.yelvertonvans.co.uk/contact.html
Mechanical Engineer with 20 years experience in the auto industry, 8 yrs in formula 1 engine testing
Thanks Matt.I have checked with the first two, the third site is down.I've had prices back, less expensive than the main dealer, but still enough not to make the repairs cost effective so the car will be off.At £700+vat for the gearbox controller ecu alone.Shame, but there you go.Cheers XXXXX XXXXX
one other place to try are these two firms as they may be able to repair it