2000 Audi A6, 4.2

I’m new to the Audi World, about a month ago I picked upa 2000 A6, 4.2 with 121,000 miles. Mostthings seem great, fun ride, but many sensor issues. I’m picking through them and learning alot. One problem I had was the car wouldnot start. All dash lights came on, butnothing. I would use the key fob to lockand unlock the car and then it would start right up. Last night, I could not get it to start. Pulled the battery cable andreconnected. Nothing, but the nav. Systemstarted talking to me and the security system seemed to be acting funny. Let the car sit overnight in a Taco Bellparking lot (glad no kids messed with it) and in the morning, it started rightup. Drove it home and with it runningran a scan tool (neighbors). Clearedseveral central locking system codes (passage doors, trunk, and internal motionwhich my son set off last night playing in the car at Taco Bell). Shut car off and now it will not startagain. Called Audi dealer and they saidit was not the immobilizer system because the car would start and then shutoff. I asked if the key fob batteriescould be getting weak, they said no, the key fobs only work doors and would notkeep car from starting. They jumpedright to the steering column and key cylinder. They want me to bring it in for several days to diagnose. $$$$$$$$. I have read a lot about key cylinders andloose wires. I might look there. Could my car battery be low???? I did try jumping it last night butnothing. I need to figure out what isgoing on, because I have not faith in the car right now and don’t want my sondriving it.

2000 Audi A6, 4.2

Let car sit for an hour and it started right up. Did it several times. Also locked and unlocked doors and it started?????

rocketman4321

Had you just driven to Taco Bell and then you tried a restart and it failed? I haven't experienced it on my Audi, but it's a classic symptom of a bad crank position sensor--fails hot or warm. Bosch fuel pump relays are also known to fail warm--the solder joints crack and open up with heat--very common on Volvos that put the relay inside the passenger compartment. Could you hear the pump run in key position two?

Even more basic--starter solenoid? Sometimes as those begin to fail you get a grinding on start as the solenoid does pull in all the way. But not always a symptom--can just die.

However, those don't explain the security system. You might also try swapping any other relevant relays. Cleaning ground points is also always good, but I wouldn't think that would give you such an on/off behavior.

2000 Audi A6, 4.2

Thanks for the input rocketman. I'll check some of those things. My son and wife took the car about 20 mins away. They stopped and started several times, and the one time at Taco Bell it would not start (would have been last stop for the day). I looked the fool pulling fuses, battery cables and more with the nice fancy car in the parking lot as beater cars pulled in and out. Yesterday I took the battery out and ran to autozone to check, it was fine. Cleaned terminals and replaced. It did not start for three tries, on fourth it started. Ran it five mins and turned it off. Again did not start for two tries and third it kicked on. One more round and same thing. When I replaced the battery the nav. system came on, on my first try and letting key sit in the "on" position. Strange. Could it be a loose wire in the key cylinder??


I've seen several comments on crank position sensors. How would that affect starting. If the sensor thought things were in the wrong place, the car would never start. I hear nothing from the starter at all when there is no start, just some light ticks from the area of the brake master cylinder, nothing else. Explain the crank position sensor - I've seen other post with the same comment???


Thanks again - electrical issues are a bear to pin point.

SloopJohnB@mac.com

engine cranking/turning by starter. That's key…if your engine isn't turning over it's either the battery, the starter solenoid, the starter itself (which includes the solenoid), or the control system leading to the solenoid. You can most easily check the battery voltage during attempted starting..if it drops below 11v you have a battery or alternator not charging it problem or a bad cable or cable connection somewhere if not at the battery at the starter. Do you still have a good belly pan under the engine or was it removed? That bellypan stops a lot of corrosion and problems.

You could go medieval on the system and run a remote starter switch/wire to the solenoid and the positive battery post. When the starter won't turn over with the key, leave the key on and hit your remote starter switch. If the engine turns over, your problem is generally upstream of the starter. If the starter doesn't turn over, it's your starter.

You've got a 15+ year old car…a worn out starter would not be unusual.

I'm not all that sanguine about auto zone battery testing facilities or competence…that's why I have my own battery chargers and load tester.

axelchief

I've just buyed an old A8 D2, however nice/130 K. I guess I've got it cheap, cause I also have these cranks, but wont start situations. My 2,8 12 valve cranks, fires, but then dies out. I can try to start up to (until now) 8 times, before it fires and keep running. I was to a delaer today, and by time he will make a diagnose, he said. Hope I can survive until that, but he could anyway not promise me any concrete answer of the situation. Irritating, and this is my first Audi, sice 1982 Audi 200 5T (Europe).

CRuby

When starter went bad on my son's A6 we just had a slight click from the starter solenoid, which is located toward lower PS, behind alternator. Possibly that is the "light tick" noise you're hearing. PITA to get to it, if that is your problem.

axelchief

I'm thinkin' and may be I'll change the Crankshaft Position Sensor (part FSE51609)(G4 black connector). But where is this sensor located on the AAH engine? Is it on left hand (driver) side rear? I observe this sensor cost just a 50 box or so. Actually, I can't use the car without thrusting it! (Engine cranks, but wont ignite normal (sometimes).

SloopJohnB@mac.com

Like the remote starter trick.

axelchief

I was to another dealer today, and he said (was 90 % sure) that this is a symptom of the starting interlock system. I also have observe in the dash, a key-symbol, which he sad has to disappear before I can start. I've done what he said, and today I haven't had any mis-startings (?). But anyway, there has to be a relay in that interlock-system which deny the engine to start, I guess.