ECU fail? Can't connect scanner to the car... Could this really be true?

[nogaroblu]

So Saturday afternoon I take the S4 to the car wash, I get home and turn it off, 20mins later I get into it and it won't start. It was cranking but wouldn't fire up, I go back inside grab my spare key and same thing, let it sit for another 20mins and it starts and drives fine, then all of a sudden it cuts out as if I turned the key to the off position after maybe 30mins of driving and won't turn back on.

Sunday I return to the car it starts, drive it for an hour and half around the neighborhood, cruising, beating on it, I couldn't get it to cut out like it did the night before. Now, Monday I drive to work (15miles) no problem, I drive home later in traffic maybe an hour or so and a mile from home it cuts out again and won't start back up.

I've done research from Saturday night and cannot come up with a similar problem anyone else has had. I have no lights on the dash, and my scanner won't connect. So I went to the local auto parts store, they tried to scan with a Bosch scanner and it wouldn't connect either?

I read somewhere that the ecu would be the problem? It's bone stock, no modifications at all. Any advice would be greatly appreciated.

[p3u]

Alternator and or battery is most likely. Without being there that's my educated guess.

[nogaroblu]

Would a battery cause the car to cut out? It turns over no problem, from my experience with previous cars and battery being bad it would just click and not turn over

[bmwpower603]

Would a battery cause the car to cut out? It turns over no problem, from my experience with previous cars and battery being bad it would just click and not turn over

It is deff a combo of alternator, and/or battery. Sounds like alternator though.

[icanfly]

Have you opened the ECU box to see if something got wet?
There are several fuzes/wire connections etc in the ECU box. If you have a bad seal on the ECU box and it's getting wet and or moisture in there, you can be causing a short in the system. What you are talking about doesn't sound like the "Alternator/Battery" problem because you'd get some indication of a warning. If the car works and then doesn't and then does and then doesn't... without symptoms of slow to start or low level lighting etc. Then you are having an electrical issue. I had a similar issue when the secondary board of my ECU came of the main board - resulting in a "ran fine when I pulled into the parking lot, but now wont start/click/anything - totally dead".

Check out Joeys motor pull DIY Specifically Phase 5 where he shows the removal of the engine harness stuff... skip all that and just pay attention to the "opening the ECU Box" and pulling the guts out part. Be extra careful when you pull the lid that you don't bust the back corner of the lid off (like my effing original mechanic did... thanks duush!). you'll want to use a super small ratchet to get to the back bolts. Take your time and go slow.

This will let you see the state of the ECU, the harness and connectors and the fuse block that sits in that box. Ultimately this will either validate or rule out any "wet ecu/wiring" problems you might have. Further, I'd suggest this route as you mention that it started after the carwash.

good luck

[1.8t]

Could be fuel pump failing. I doubt its alternator or battery, if your battery is dead, it can't magically charge itself up while the car is off and start. If your alternator has failed then you'll get a decent amount of error lights on the dash before losing power.

My guess is fuel pump.

[nogaroblu]

Thanks guys I appreciate it. I went to a couple of shops and they all pretty much turned me down, and with needing a car, to get to and from work, I just took it into Audi. They gave me a loaner and said it would be a few hours ($149.99) for the diagnostics. Well an hour or so later the service advisor calls saying "the car won't communicate with their scanners" and ok I knew this and I told you over the phone, before I brought it in, and when I was handing over the keys. What ticked me off is when he called and said that and added, "so would you like us to continue investigating?" So I go well yes of course, and he jumps to say "it's up to you because it'll cost a couple more hundred dollars". Excuse me?

Needless to say I got a little hot headed and told him what they need to do isn't my problem, I came in to find the problem not to get bent over, he claimed he would talk to the "manager" and calls back saying they will investigate and call me back tomorrow. Anyone ever pay more than the stated $149.99 for diagnostics? Anyone ever experience Audi basically stating "well we tried, you're on your own"?

[Concavitor]

Weak battery likely

[icanfly]

That diagnostic fee is usually to 'plug in the scanner and read any codes'.

Did you get in writing that you've brought them the car because you tried to get it to connect to the ECU and are delivering the car for diagnostics as a result of "Can't connect to ECU" errors and that the ask you had was for them to go further than just trying to 'read the codes'?

that would be helpful when going to a manager to say "I'm not a newb. I know my ECU can't connect... I brought my car here for you to tell me WHY it wont connect.".

[nogaroblu]

That diagnostic fee is usually to 'plug in the scanner and read any codes'.

Did you get in writing that you've brought them the car because you tried to get it to connect to the ECU and are delivering the car for diagnostics as a result of "Can't connect to ECU" errors and that the ask you had was for them to go further than just trying to 'read the codes'?

that would be helpful when going to a manager to say "I'm not a newb. I know my ECU can't connect... I brought my car here for you to tell me WHY it wont connect.".

yes, when i called (before dropping it off) and when I was handing over the keys, they took down notes, and I stated that I went to a few places who offer free diagnostics and none of them were able to successfully connect to the car, also the fact that there is no fault lights currently on the dash.

I will see what they say when they call me today. I will keep you guys posted.

[pandapod]

I had a similar issue on my 1992 Honda Accord back in high school...obviously nowhere near the same car, but i experienced similar symptoms and it was very hard for my mechanic to diagnose the issue. The car would die on me while driving, spurt back to life, die, repeat, turn off, wouldn't start, but then would start randomly and be fine for a bit, then repeat the problem. It ended up being the ignition coil/distributor pack.

This is most likely not your problem, but something you may want to consider...

[RedS4avant]

Have you opened the ECU box to see if something got wet?
There are several fuzes/wire connections etc in the ECU box. If you have a bad seal on the ECU box and it's getting wet and or moisture in there, you can be causing a short in the system. What you are talking about doesn't sound like the "Alternator/Battery" problem because you'd get some indication of a warning. If the car works and then doesn't and then does and then doesn't... without symptoms of slow to start or low level lighting etc. Then you are having an electrical issue. I had a similar issue when the secondary board of my ECU came of the main board - resulting in a "ran fine when I pulled into the parking lot, but now wont start/click/anything - totally dead".

Check out Joeys motor pull DIY Specifically Phase 5 where he shows the removal of the engine harness stuff... skip all that and just pay attention to the "opening the ECU Box" and pulling the guts out part. Be extra careful when you pull the lid that you don't bust the back corner of the lid off (like my effing original mechanic did... thanks duush!). you'll want to use a super small ratchet to get to the back bolts. Take your time and go slow.

This will let you see the state of the ECU, the harness and connectors and the fuse block that sits in that box. Ultimately this will either validate or rule out any "wet ecu/wiring" problems you might have. Further, I'd suggest this route as you mention that it started after the carwash.

good luck

Another vote for this

[nogaroblu]

Ok I finally got a call from Audi, so they still cannot get their scanners/computers to connect and communicate with the car, BUT they are sure the random cut out and no start issue is due to a crank position sensor. Anyone know where this is located? They want $700 for the sensor and labor! I've tried to search and no luck with any diys or diagrams.

[924Carrera]

Cheapest place I found the sensor was $47 at AutohausAZ for the Bosch one. Install is a pain, as seen in this thread, but doable yourself for far less than $700. Part number is 077905381F, in that thread below ECS Tuning evidently jumped the gun and posted a link to B5 S4 sensor instead, which looks very similar but is not the same.

http://www.audizine.com/forum/showth...r-(Code-P0322)

[nogaroblu]

Cheapest place I found the sensor was $47 at AutohausAZ for the Bosch one. Install is a pain, as seen in this thread, but doable yourself for far less than $700. Part number is 077905381F, in that thread below ECS Tuning evidently jumped the gun and posted a link to B5 S4 sensor instead, which looks very similar but is not the same.

http://www.audizine.com/forum/showth...r-(Code-P0322)

appreciate it!

[Jake@JHM]

Is the car tuned?

[nogaroblu]

Is the car tuned?

Nope, completely stock

[ZimbutheMonkey]

Have you opened the ECU box to see if something got wet?
There are several fuzes/wire connections etc in the ECU box. If you have a bad seal on the ECU box and it's getting wet and or moisture in there, you can be causing a short in the system. What you are talking about doesn't sound like the "Alternator/Battery" problem because you'd get some indication of a warning. If the car works and then doesn't and then does and then doesn't... without symptoms of slow to start or low level lighting etc. Then you are having an electrical issue. I had a similar issue when the secondary board of my ECU came of the main board - resulting in a "ran fine when I pulled into the parking lot, but now wont start/click/anything - totally dead".

Check out Joeys motor pull DIY Specifically Phase 5 where he shows the removal of the engine harness stuff... skip all that and just pay attention to the "opening the ECU Box" and pulling the guts out part. Be extra careful when you pull the lid that you don't bust the back corner of the lid off (like my effing original mechanic did... thanks duush!). you'll want to use a super small ratchet to get to the back bolts. Take your time and go slow.

This will let you see the state of the ECU, the harness and connectors and the fuse block that sits in that box. Ultimately this will either validate or rule out any "wet ecu/wiring" problems you might have. Further, I'd suggest this route as you mention that it started after the carwash.

good luck

x3

It may be possible that it's a battery issue as the ECU has a threshold voltage it needs to function.

However, as someone who's bricked a few ECU's while learning to tune Motronic, your scenario (turning over with no communication) is exactly what happens when you have an ECU issue.

Look at it this way, you've wasted anywhere from $150-600 on getting those useless tits at the dealership to tell you what you already know, plus how many hours of your time bringing the car to and from different shops, why not take the 30 min, pull the ECU and have a look to make sure you don't have a short.

As well if your ECU has been compromised, I might suggest making a bench flasher and backing up your EEPROM and immobilizer data in case your ECU takes a complete dump on you. (easy to do with an ebay VAG-COM cable and free software from Nefmoto.com)

Bear in mind that if you completely loose your immo data, you're going to have to get the dealership to recode your cluster to any replacement ECU that you buy. However, you can buy a replacement ECU for $100 and clone it, so I highly recommend getting that data backed up ASAP.

[ZimbutheMonkey]

Ok I finally got a call from Audi, so they still cannot get their scanners/computers to connect and communicate with the car, BUT they are sure the random cut out and no start issue is due to a crank position sensor. Anyone know where this is located? They want $700 for the sensor and labor! I've tried to search and no luck with any diys or diagrams.

Also, how do they explain the no communication??? A bad crank sensor shouldn't result in a no communication error.

Lol, do you really want to take the advice of a shop who charged you $150 AFTER you told them that there was a communication error, to tell you "derrrp we found out that your ECU won't communicate with our scanner, deeerpp deerpp..."

[nogaroblu]

UPDATE

I call Audi on Friday to see if they will have my car "put back together" and ready to be picked up that evening. Well, the service guy that was working with me was off (Friday & Sat), and the guy that was filling in was told there is no diagnosis yet and I should just keep the loaner until they call me....
I told the guy, that I was called on Thursday and told it was the crank position sensor and he said he just talked to the techs and they have no diagnosis yet?

Now I am pretty pissed...I will call later and see what they tell me.

[nogaroblu]

Also, how do they explain the no communication??? A bad crank sensor shouldn't result in a no communication error.

Lol, do you really want to take the advice of a shop who charged you $150 AFTER you told them that there was a communication error, to tell you "derrrp we found out that your ECU won't communicate with our scanner, deeerpp deerpp..."

I would most certainly back it all up, if only I could get something to connect to the car via OBD2

Right, I agree, and I told the service advisor from the start (on the phone before I dropped it off and when I was handing over my keys). I never thought Audi would put anyone in that type of position, we shall see what will happen.

[nogaroblu]

so Audi just called, now they are not sure if its the crank position sensor. They think the cluster may be shorting.... So they are pulling a cluster off another S4 and will install it into mine to see if they can get their computers to communicate with the car = which will hopefully allow them to diagnose it

UPDATE

Audi has confirmed the cluster is good, now supposedly they are sure it is the ABS module? which they claim is the reason no computer is able to connect to the car successfully
They are still recommending replacing the crank position sensor.

[Lucca M]

Well sounds like Audi has some really well qualified specialists up there !


Something got wet and its probably ecu, abs module? Lololol.. What a bunch of idiots.


Like one of the guys said it previously, you need to see if the ecu is fried or not, find somebody with bench flasher so he can check it for you. Dont waste more money at idiotdealership.

[RedS4avant]

I predict the dealership giving you the run around until you give up and trade your S in for pennies and rollout of there in a b8 from them. I think that is half their sales model

[marcmo60]

so Audi just called, now they are not sure if its the crank position sensor. They think the cluster may be shorting.... So they are pulling a cluster off another S4 and will install it into mine to see if they can get their computers to communicate with the car = which will hopefully allow them to diagnose it

UPDATE

Audi has confirmed the cluster is good, now supposedly they are sure it is the ABS module? which they claim is the reason no computer is able to connect to the car successfully
They are still recommending replacing the crank position sensor.

Looks like your in the Chicago area, which dealer are you at since I'd like to avoid them. If it hasn't been suggested already I would recommend taking your vehicle to Chicago Performance and Tuning.

[nogaroblu]

I predict the dealership giving you the run around until you give up and trade your S in for pennies and rollout of there in a b8 from them. I think that is half their sales model

LOL well then they should have given me a S4 loaner, not a Q5 these 2.0t are sooooo slow

[nogaroblu]

Looks like your in the Chicago area, which dealer are you at since I'd like to avoid them. If it hasn't been suggested already I would recommend taking your vehicle to Chicago Performance and Tuning.

Audi of Westmont
Never heard of Chicago Performance and Tuning, next time I will definitely contact them.

[Shabayaba]

Have this same issue crank no start abs light on

- - - Updated - - -

Have this same issue crank no start abs light on