oil pressure light and buzzer.

[kev1]

I have a problem with my transporter 2.5 tdi. After I have been driving for about 15mins when the rev counter hits 1500 revs I get the three bleeps and the red oil can lights up it promptly dissapears after about 5 seconds when the revs rise above 1500.
I've been to a vw main dealer had it on the diagnostic it shows nothing. I've had the sensor replaced and this seemed to cure the problem for a few weeks but then it came back.
The strange thing is it dosen't do it every time I hit 1500 but when it does do it, it's always at 1500 revs. Has anyone else experienced this problem and if so what's the cure.
many thanks kev. :confused:

[Herman.58]

Hi Kev, that is one weird problem.. I 'm sorry I havent come across/heard of a problem like this before on any forum. The only thing I can think of is this. Check if there are two oil pressure sensors??..low pressure warning and high pressure warning. If so it could be a fault on the high pressure sensor. Its a long shot and I maybe completely barking up the wrong tree. Sorry I dont have definitive answer coz its sounds like a maddening fault.:beerchug:

[kev1]

Thanks for replying Herman, it's just been in this week for a cambelt and water pump. I asked whether there was a second pressure sensor they said not to their knowledge. The engine sounds smoother and pulls a bit better but still every so often bleeps and flashes. :(

[Herman.58]

Ok Kev, I told you it was along shot!. I suppose your next step is to check the wiring from the sensor to the buzzer.............its the fault occuring at 1500 revs that gets me!!:confused: . If it was just intermittent at non specific revs I'd go look for a wiring fault or blocked crankcase breather or similar. It almost sound like an ecu fault, but not showing on vagcom??? I'd go for a wiring fault next if there is no high pressure sensor.
:beerchug:

[carbon]

I think Herman.58 may have been onto something about two pressure sensors. I just read on another forum that there can be two sensors on the Transporter, it may depend on the engine but definitely worth looking into in more detail. I’ve just tried looking on vagcat.com but it seems the server is down so I can’t confirm this at the moment. I’ve also had a look at an online catalogue which lists two.

[kev1]

carbon thanks for the reply, my cambelt was not done at a vw dealer so possibly they would not have known. I wonder if there is a site that shows the engines in detail. I'll have a look.
cheers Kev.

[JIM WHITE]

guy's i too have this problem of the oil light and buzzer , i have not related it to a rev range and it only happens intermitantly some times 1 a month sometimes 3 times a week - the garage i bought the t4 from say's its a common problem with VW and they have change lots of sensors with no cure on the VW range not just T4. Great motor apart from this. :o (T4 Caravelle variant auto 2.5 tdi 2003 63K)

[kev1]

Jim, I got in touch with a vw dealer and a guy that works there said check the needle switch at the top left of the bonnet opening. It's switched by the bonnet opening and closing. I checked mine and it was a bit stiff, so I pumped it a few times to loosen it up. i went on a drive of about 100 miles and the buzzer went off twice, which is less than normal I'm going to get the switch replaced next week see if that sorts it. :o

[JIM WHITE]

Jim, I got in touch with a vw dealer and a guy that works there said check the needle switch at the top left of the bonnet opening. It's switched by the bonnet opening and closing. I checked mine and it was a bit stiff, so I pumped it a few times to loosen it up. i went on a drive of about 100 miles and the buzzer went off twice, which is less than normal I'm going to get the switch replaced next week see if that sorts it. :o


Thanks for the info -- I will check it in the morning. Bit strange that a bonnet switch can activate such an important monitoring warning device and if this is known to VW why don't they publish it and save us all a lot of hassle

i have just came across another post on this site and the are talking about wires connected to the alternator not connecting properly !!!!!!! this could be a gremlin hunt with everybody having a guess Cheers

[carleton]

I think Herman.58 may have been onto something about two pressure sensors. I just read on another forum that there can be two sensors on the Transporter, it may depend on the engine but definitely worth looking into in more detail. I’ve just tried looking on vagcat.com but it seems the server is down so I can’t confirm this at the moment. I’ve also had a look at an online catalogue which lists two.
My caravelle 2.5 has this problem, changed the pressure sensor,( there is only one fitted to my 2003 model I looked it up at VW parts on the computer) and it made no difference. I removed the sensor and fitted a oil pressure test gauge in its place. Bad news, oil pressure is low 1 bar at 2000 rpm, it should be 2 bar at 2000 rpm. what I don't understand is why the oil warning comes on at 80 mph on the motorway and never at idle, I think there are two problems, 1 oil pump, and 2 wiring problem on circuit board behind instrument panel. going to look at oil pump now, I will keep you posted.

[carleton]

Update to my previous post, Oil pump worn out, with only 170000 miles. The engine had no rattles or signs of anything wrong, just the oil light flashing randomly, about 4 times every 10 miles, and at any speed.

[carleton]

The last update on the oil pressure light coming on randomly.
The oil pressure light is not just a switch the earths the circuit when no oil pressure is sensed, it must be a bit more electronic, and passes its info on to a black box, hidden in the depths. so when ever yours comes on, after changing the sensor, just to eliminate that bit, will mean you have low oil pressure.
New pump fitted in mine, and all is well, no more lights, no more low pressure.
My engine has survived 3000 miles of intermitant oil light coming on, 10psi idle hot and 15 psi at 2000rpm hot. when I had the low pressure the engine sounded slightly tappety. New pump no tappet noise.