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Flashing oil light and rev counter not working....

Old 06-30-2014, 11:01 PM
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Default Flashing oil light and rev counter not working....

Hi Guys
I have just been given a 1998 A8 D2 4.2 from a work colleague as it has a couple of issues.

The colleague informed me last week that the red oil can light had started to come on even though the oil level was known to be correct.
I have owned Audi's before so immediately suspected an oil pressure problem.....

At the same time I remember him saying something about the rev counter also playing up at the same time. Tbh I dismissed this at the time and told him they were not linked....

Anyway, I drove the car home last night (15 miles) and as soon as the car is put into drive the oil light comes on.

On the drive home a couple of times the rev counter that was not working at all would start working. At the same time as it would start working the oil light went out.......

At the end of the journey the rev counter worked perfectly and the oil light stayed off.

I am now thinking that the problems are most certainly linked??

Where would be the best place to trace the signal issue to the rev counter?

I am not sure if this is relevant but my colleague has not used the car very much at all over the past year or so. I have known it to be parked up for many months at a time. I did notice when I had a quick look under the bonnet that around the scuttle area is filthy. He must have left it parked under trees...

When he first brought the car in to show me I wanted to plug in my basic diagnostic machine. We spent an hour trying to locate the OBD port with no success. I removed the trim under the steering wheel and it is not there. Google mentioned that it may be under the ash tray; in this specific model the ash tray has a wooden sliding drawer type opening and it does not look like it comes out easily.
If anyone knows where the socket is I would love to hear!?

Many, many thanks in advance for anyone who may be able to offer some advice!
Old 07-01-2014, 05:07 AM
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The diagnostic port should be under the knee bolster on the driver side (atleast on my '97). You do not need to remove any trim panels to access it. If it is in the ash tray area there may be a small cover over it.

As far as the oil light, the oil pressure sending units are known to go bad. Its located on the passenger side of the engine on top of the oil filter housing. here is a link to a replacement sending unit from autozone: Oil Pressure switch Also try changing the oil and filter (I use the Mann filter). For some reason on my '97 when it gets close to oil change time the oil light will come on at low rpms/cruising. Change the filter and oil and all is fine until the next oil change.

Can't help you with the rev counter. Hopefully someone else can help you out with that.

There's some good diagnostic software specifically for VW/Audis at www.ross-tech.com They have a free version VSDS lite but you will have to get a cable from the ebay or the like. They also have licensed versions that do much more.

Also check out Audi Pages for lots of technical articles and maintenance how to's. Under the oil cooler replacement tab there is a picture showing where that oil pressure switch is.
Old 07-01-2014, 07:24 AM
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Originally Posted by nyrobbie77
The diagnostic port should be under the knee bolster on the driver side (atleast on my '97). You do not need to remove any trim panels to access it. If it is in the ash tray area there may be a small cover over it.

As far as the oil light, the oil pressure sending units are known to go bad. Its located on the passenger side of the engine on top of the oil filter housing. here is a link to a replacement sending unit from autozone: Oil Pressure switch Also try changing the oil and filter (I use the Mann filter). For some reason on my '97 when it gets close to oil change time the oil light will come on at low rpms/cruising. Change the filter and oil and all is fine until the next oil change.

Can't help you with the rev counter. Hopefully someone else can help you out with that.

There's some good diagnostic software specifically for VW/Audis at www.ross-tech.com They have a free version VSDS lite but you will have to get a cable from the ebay or the like. They also have licensed versions that do much more.

Also check out Audi Pages for lots of technical articles and maintenance how to's. Under the oil cooler replacement tab there is a picture showing where that oil pressure switch is.
Thanks for taking the time to reply.....

Well I did have a look at the car this morning. The first job was working out why the carpets in both front foot wells are soaking!!!

I found a guide on-line and it would appear the main scuttle area drain channel is blocked and water has been travelling down the drain plugs into the cabin.

As for the oil light, it is definitely linked to the rev counter. You could be driving, see the rev counter needle drop to zero and the oil light suddenly comes on. It is happening intermittently.

I am thinking that maybe some of the electrics in and around the drivers foot well have got wet.....

I do think though that it may be worth changing the oil pressure switch anyway to see that if makes a change if it is a cheap part that is easy to switch over.

Cheers
Old 07-01-2014, 11:19 AM
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Well I did have a look at the car this morning. The first job was working out why the carpets in both front foot wells are soaking!!!
Cheers
Yes, the drains in the cowl area do like to get clogged up. follow the instructions on www.audipages.com as there are three sets of drains that can plug up. best to clear them all out.

sounds like you're on the right track with the water/electronics idea. if you pull up the passenger side carpet, you will see a particle board cover near the firewall. it's held in by a couple screws, under it is a relay/wiring center. I'm betting that water has gotten into there and could be the source of your gremlins.
Old 03-14-2016, 05:11 AM
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ahp
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Originally Posted by TROOPER88
Hi Guys
I have just been given a 1998 A8 D2 4.2 from a work colleague as it has a couple of issues.

The colleague informed me last week that the red oil can light had started to come on even though the oil level was known to be correct.
I have owned Audi's before so immediately suspected an oil pressure problem.....

At the same time I remember him saying something about the rev counter also playing up at the same time. Tbh I dismissed this at the time and told him they were not linked....

Anyway, I drove the car home last night (15 miles) and as soon as the car is put into drive the oil light comes on.

On the drive home a couple of times the rev counter that was not working at all would start working. At the same time as it would start working the oil light went out.......

At the end of the journey the rev counter worked perfectly and the oil light stayed off.

I am now thinking that the problems are most certainly linked??

Where would be the best place to trace the signal issue to the rev counter?

I am not sure if this is relevant but my colleague has not used the car very much at all over the past year or so. I have known it to be parked up for many months at a time. I did notice when I had a quick look under the bonnet that around the scuttle area is filthy. He must have left it parked under trees...

When he first brought the car in to show me I wanted to plug in my basic diagnostic machine. We spent an hour trying to locate the OBD port with no success. I removed the trim under the steering wheel and it is not there. Google mentioned that it may be under the ash tray; in this specific model the ash tray has a wooden sliding drawer type opening and it does not look like it comes out easily.
If anyone knows where the socket is I would love to hear!?

Many, many thanks in advance for anyone who may be able to offer some advice!
Hi, did you ever resolve the issue with the oil light and rev counter?
regards ahp
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