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How to Troubleshoot the oil light and buzzer on 86-92 Vanagons

August 5, 2014 18 Comments Ask Ken, Engine, Wiring Ken Wilford

A common problem with 86-91 2.1l Vanagons is the flashing oil light with buzzer sounding. This article only effects 86-91 2.1l waterboxer Vanagons. If you have an earlier Vanagon (80-85) please refer to my previous article about the oil light coming on:

http://www.vanagain.com/stop-your-oil-light-from-flickering/

Please Note!

I want to stress that if your oil pressure light comes on, please pull over immediately and shut the engine off. Don’t let the fact that you read this article and you think that you know why this is happening and it is just a normal thing for Vanagons stop you from doing what common sense dictates. You never know if what you are experiencing is a real oil pressure problem or a false alarm. It is not worth taking the chance, pull over, and check things out!

Usually folks experience the oil light flashing/buzzer syndrome after extended driving. You go to get off at an exit ramp and then the oil light comes on flashing and the buzzer sounds. What is going on?

1. Understanding how the system works

First of all let us understand how this system works. You have two oil pressure senders which are monitored by a control board located behind your speedometer. One sensor is located in the base of the engine between the push rod tubes. This is called the .3 bar sensor and the plastic part of it should be brown in color. This sensor is for the oil light only (no flashing or buzzer). This is the same sensor that has been used on VWs for the past 30 years. It senses when the oil pressure falls below .3 bar (around 5 psi). At this point the sensor grounds itself and the light comes on. The control board only looks at the input from this sensor when the rpms of the engine are below 2000.

The other sensor is located near the water pump. This is the sensor that causes the oil light to flash and the buzzer to sound. You should see a brown wire going down near your ignition distributor to this sensor. This is called the .9 bar sensor. The control board that monitors the two sensors only looks at this one when the rpms go above 2000. How is works is when oil pressure is above .9 bar (aprox 13.23 psi) the switch inside the sensor is closed. This grounds the sensor and this keeps the light off. It works the opposite of the .3 bar switch which comes on when it is grounded. As you rev the engine above 2000 rpm the control board looks at this switch to see if it is still grounded. If it is the oil light and buzzer stay off. If the pressure goes below .9 bar while the engine is above 2000 rpms then the switch inside the sensor opens (pressure holds it shut) and the buzzer and flashing light start.

2. Troubleshooting the problem

Now that we know how these sensors work we can start to troubleshoot them. First of all the .3 bar sensor and it’s problems and methods of troubleshooting have already been addressed in an earlier article http://www.vanagain.com/flicker1.htm. If you are having the oil light flickering or flashing on and off at idle then please read this article. However if you are having the oil light come on flashing with the buzzer then continue.

The very first thing to check if you are having this problem is the oil level. If you are low on oil your oil pressure can get low. This is why this warning system is there to prevent us from having problems due to an oil leak or our own negligence.

Next you want to be sure that your oil is clean and not diluted with gas. Smell the oil. Does it smell like gas? You may have a leaky injector that is diluting your oil. This will thin it and reduce your pressure.

What weight oil are you using? I would recommend 20w-50 oil for all waterboxer engines that have over 100k miles on them. If you are using a lighter weight oil try changing the oil and see if this helps.

What oil filter are you using? You want to see a black oil filter on the engine. Mann or Mahle or VW filters ONLY! Fram, Bosch, and any other color of the rainbow (blue, red, yellow, grey, etc.) can cause a low oil pressure condition so don’t use them.

Now that we have covered the basics you want to check the wiring to the .9 bar sensor. As we have said the sensor tells the buzzer and light to come on when the control board sees an open in the circuit. This could be caused by the sensor or it could also be caused by the wiring going to the sensor if it becomes broken somewhere along the run. You can easily test this by unplugging the wire from the sensor and grounding it to the engine of the van (usually there is a male spade connector on the side of the ignition distributor where you can plug this wire into). If the wiring is good then your oil light and buzzer will stay off at all times. If there is a break in the wiring usually the buzzer and light will come on immediately upon revving the van above 2000 rpms. At this point you are going to need to examine the wiring, try to find the break and repair it.

If you have grounded the sensor wire and it has made the buzzer and flasher stop the next step is to replace the sensor. You could check the sensor with an oil pressure gauge and wiring up a light to show you when the sensor is grounding or not but most folks don’t have the skill or equipment for this. If you do this is outlined in the Vanagon Bentley Manual. If you don’t then I would suggest just buying a new .9 bar oil sensor as they are only $6 and they are a wear item that should be replaced every 100k miles or so. Be sure that when you get the new switch the plastic part of the body is gray in color and the part number is 068919081A. This is the correct part number for this part. There is much confusion going on about this part and what the proper part number is so be sure to have the part number with you when you go to order this part to avoid getting the wrong sensor.

If you replace the sensor, plug the wire back onto it and you are still getting the oil light flashing with the buzzer then you need to have the oil pressure tested. You can do this yourself by purchasing an oil pressure test kit, or take it to a local shop and have it tested. You want to do the test with the engine warmed up (radiator fan having cycled on and off once). At 2000 rpm the oil pressure should be 19 psi or higher (19 psi is the minimum at 2000 rpm). If your oil pressure is below this then you probably have some worn engine parts like rod or main bearings and you should start saving money for an engine rebuild. Some folks install a higher volume oil pump to increase oil pressure. We sell this heavy-duty oil pump and it may work for a while (another year or so) but it is only a temporary fix for a tired engine.

If you have your oil pressure tested and it is above the minimum then you probably have a problem with the control board that controls the buzzer and flashing light. This is an “L” shaped board that lives behind the speedometer. Simply remove your speedometer and you will see it. We have these for sale as well if you find you need one. If you replace this board and you are still having problems (it happens) then you may have a problem with the printed circuit foil on the rear of the instrument cluster or the tachometer. The control board is getting a signal from the tachometer and if something is not right at the tach or with the foil circuitry in between then this could cause a false alarm.

At this point you have three options. You can continue to have the oil light flash and the buzzer come on at random intervals (very disturbing to say the least) and just ignore it (not a good idea but many people do). Second choice would be to continue to try to track down the problem by replacing the instrument cluster, etc. This can get expensive. Or you could go with the third option which would be to install an oil pressure gauge and just disable the buzzer and flashing light.  I recently did a video on how to do that which I will link below. This way you can monitor your oil pressure yourself with the gauge and the buzzer and light will never come on again. The flickering oil light will still work below 2000 rpm so you will still have the idiot light at idle. Many people do this and it is a good idea to install an oil pressure gauge so that you can know what is going on with your motor. You could mark the danger zones on the gauge with red tape just incase someone besides yourself is driving the van.

 

Now you know all that I know about the oil light flashing and buzzing problem. I hope this helps answer your questions. If you need any parts please feel free to give us a call or email or order on-line through our web store.

Thanks,
Ken Wilford
John 3:16

Comments

Ken Wilford May 19, 2017

Gary, if I installed a new motor and had a low oil pressure buzzer going off, the first thing I would do is to test the oil pressure with a gauge. You want to try to resolve this with your rebuilder as quickly as possible. You need to set up a gauge that you can see what the engine is doing when it is cold (highest pressure) and when it has fully warmed up. If you can see that it isn't a real low oil pressure condition with a gauge, then I would move on to dealing with the "L" board and other oil pressure warning system quirks. Just my advice. Ken

Gary May 18, 2017

I have the problem of the oil light and buzzer coming on after installing a new engine ..replaced the sensor already ...the part you mentioned behind the dashboard L” shaped board. ..what part number is this or what's its name to find and try and buy a new one ... thanks

Ken Wilford April 18, 2017

I would only add the Lucas Oil Stabilizer if you can drain a quart of the oil to do so. You don't want to just add it, because then you could be overfull on oil which causes other problems (kill your catalytic converter). My advice would be to just change to 20-50 as soon as you can and that should fix it. Ken

Kira April 18, 2017

Is it fairly safe to "always" use a quart of oil stabilizer when changing oil? Only in synthetic or only in regular? Also, I'm in Alaska and we changed our oil about a month ago- put in 5W-50 d/t low temps. We haven't driven it but a few 30-40 mile trips but all ran well. I shipped it to Washington last week and my uncle picked it up and drove it to Portland. They called and informed me that the oil pressure light/buzzer went off a few times, typically when going up hill or moving well so >2000 rpm. They pulled over and checked oil several times- all was good. My plan was to change the oil when I get there: to 20w-50 synthetic and ensuring I have a Mann filter. Should i add the stabilizer or just see what happens with that?

Ken Wilford May 17, 2016

I would use Roadhaus.com and find a local VW shop he can take the van to and get the oil pressure tested. I know it is a new motor, but if it is a real oil pressure issue then you should find out as soon as possible. If not then you could have an oil pressure gauge installed and disable the blinking light thing. They are known for having false alarms due to wiring issues, but it is better to be safe than sorry. If you find the low oil pressure is a real issue then I am sure Go Westy will warranty the engine. If you drive it until it blows up then they will not because they will say you abused it.

Bruce Martin May 17, 2016

Hello Ken, A friend of mine is on a road trip to New York. I just got a call from him that his oil light is flashing no buzzer and it only starts to happen after he's been on the highway for 15 mins or so. We live in South Florida. He stared this trip on Thursday. This all started just now and he is in Virginia area. I installed a new Gowesty motor into his vanagon about 3 months ago. He did the break-in as per Gowesty suggests. We have gone on a few 300 mile round trip, trips and this concern did not happen. Any suggestions on what this could be? I am pretty sure the motor is good since it has only 2200 miles on it. Thanks for your help!

Ken Wilford February 14, 2016

It sounds like a wiring problem to me, but I am not an expert on the late model VWs. Most of the problems you can have with the late cars can be diagnosed by plugging in a Vag-com tool and just scanning for codes. The one I recommend and use is made by ross-tech.com and it is around $250 and requires you to use a laptop with it, but it is a great tool and takes most of the guess work out of finding problems like this. Two trips to the dealer and the tool pays for itself. I hope this helps you out. If I was there, I am sure I could figure the problem out, with a manual and doing some diagnostics, but this forum is to help out Vanagon and Eurovan owners, not Jetta owners, so I have to try to keep it on topic. If you need my help with a non-van (VW of course) you can always email me through the site and I can try to help you off of the forums. Ken

Ken Wilford February 14, 2016

It could be that the circuit foil on the back of the cluster is going flaky. I have seen this more and more as time goes by. You can disable the buzzer by unplugging it and bending a pin out of the way. Here is a write up on doing this from the samba: "There is a much simpler way without any wires or soldering. That connector on the rear of the speedometer with the 6 pins, pull it from the back of the speedo. Then you can see the pins exposed in the back of the speedo. The outside end pin of the group of 4 pins is the one to touch. Push it over to the side. Then put the 6 pin connector back over the other pins making sure the outside end pin stays bent out of the way and that the pin does not go back into the connector hole. That is all you have to do. This removes the rpm signal input so the oil warning board only looks for the lower pressure switch and doesn’t care about the missing higher pressure switch." That is the easiest way to disable the buzzer without losing your oil light entirely. If the rest of the cluster is still acting up then you could try to find a good used one, or try the Go Westy cluster repair harness (expensive but it works). Let me know if we can have you further. Ken

Ken Wilford January 8, 2016

I thought I would post Tony's latest email to me if you have been following his poor heat problem: Message: Hey Ken O.K., got the whole shmir installed. Seems to work great. Now we get heat in minutes instead of miles. The heat gauge pointer moves to the red light and stabilizes. I'm completely satisfied, can't remember when I had that much Winter heat. You were right about the bad thermostat, The dealer I went to must have had a stock of bad ones to begin with.... Tnx ! Tony Sudney

Dips January 7, 2016

Hi Ken... I am having a similar issue with my 2013 VW Jetta Sportswagon 2.5L SE (59500 miles). Last week twice the buzzer and red flashing oil pressure light came on, I was on a ramp. It asked me to stop engine. I took it to a mechanic who looked at the oil level which was more than the required top. He replaced it (said the earlier was thick like honey). The red flashing oil pressure light still comes on when i take a sharp turn. And thereafter it continues flashing till vehicle is stopped. I took it to VW service center since its still under powertrain warranty. They tested the oil pressure at 2000 RMP and found it to be at 2.9 to 3.0 bar which is within VW recommended spec of 2.7 bar. They suggested that there seems no problem with engine and pressure is building up fine. They said it cld be electrical issue. They have directed me to change the oil pressure sensor to begin with. I shall be doing that. My question still remains - Why does the red flash occur at sharp turns? Have the VW guys diagnosed correctly? They conducted oil pressure test while the vehicle was stationery. But what if the pressure is really dropping off at sharp turns?

Elliott December 31, 2015

Thanks for this article. I've replaced the sensor. I have no idea how to begin troubleshooting the wiring to the front panel. Mine often continues to buzz even when I am stopped at a light and rpm is well below 2,000. Could the problem be in my instrument cluster? It's got a number of other issues like the coolant level is almost always flashing (even though I've changed that sensor too), and recently the speedometer has stopped working. The tach used to be intermittent but that now works for the most part. At some point on a cross country trip a mechanic installed a light as a low oil pressure warning system. Is there an easy way to just disconnect the buzzer inside the instrument cluster? Also what's the chance all of of this could be solved with a replacement instrument cluster? Thanks again!

Tony Sudney December 5, 2015

Hey Ken I'm the one with the poor heat problem. I did also experience the low oil pressure/buzzer problem. I and my #2 son are electronic technicians (FCC Licensed)so we understand electrical trobleshooting. I,ll get right down to what we found. as we jiggled the wire from the .9 bar sensor, we saw an off & on intermittant while doing a continuity check. Chasing the wires we found a white connector on the firewall, had to destroy it to get it apart, the connector spades were polarized and loaded with green crud. We decided to clip the connector out of the circuit and solder the wires which of course made it a permanent connection, then we painted the wires with liquid tape.. problem gone !!!

Ken Wilford June 24, 2015

I would switch back to standard oil, be sure you are using a Mann or Mahle oil filter (black) and substitute a quart of Lucas Oil stabilizer for a quart of oil. That should bump your pressure up to the point where the buzzer is no longer coming on. If not then the next step would be to have the oil pressure tested with a gauge to see if there is a real problem or if it is just a problem with the buzzer system.

Rebecca June 21, 2015

Hi! I started having flashing light/alarm issues above 2000 RPM on my 89 Vanagon Weekender after I changed the oil. I switched from Castrol 20-50 to Castrol synthetic 20-50. Is it possible that this has triggered the sensor warning? Thanks for the detailed article--I will also follow your checklist to ensure that it's not a wiring, sensor, control board, or pressure problem.

Ken Wilford November 20, 2014

The bent prong thing is the best. You don't have the wiring so you can't ground it as you would normally to disable it in a later van. Only some 84's had the Tach (very few) so most likely the wiring isn't there and none of them had the dual oil pressure sensor warning system. I would recommend adding an oil pressure gauge. I am just getting ready to come out with a nice kit that will allow that if you are interested, stay tuned and I will be putting it in the store very soon. Ken

Liam November 20, 2014

Thank you! Can you suggest any alternative fixes? In looking at specs for '84 models, only the Wolfsburg edition had the tach and digital clock, and my attempts to locate a spare have been met with absolutely no success. I assume the bent-prong fix disables the high-rev oil pressure warning, but leaves the low-rev warning intact, correct? I assume you would suggest adding an oil pressure gauge (which I will certainly look into). Again, thanks for the quick response. LDZ

Ken Wilford November 20, 2014

Yes the reason your buzzer and light are going off is because there is no wiring from your dash to any sensor because the 84 Vans didn't have this oil pressure warning system. Bending over that one prong as was described on thesamba should fix the "problem" and allow your normal non-buzzing oil pressure light to still work properly. Ken

Liam November 19, 2014

I have a similar problem. I have a 1984 Vanagon with a tach. The foil went kablewie, verified by my mechanic. He told me that it was wired for a later model cluster (multi-plug on the bottom instead of the side) so I could get a cluster from an 86-91 van and that would work. So I found a later-model cluster, plugged it in, and everything seemed to work just fine (including the tach). As soon as I started driving, the oil pressure light and buzzer went off. My motor was in dire need of replacement (no compression in two cylinders) so I assumed that since I now had a working cluster, that my oil pressure was indeed low. Flash forward to now, I just had a newly rebuilt motor installed, and the owner called me to ask if there was something wrong with the instrument cluster, as the oil pressure light and buzzer are going off, even though the motor definitely has plenty of oil pressure. I read about this fix on thesamba.com...thoughts? Fix: "There is a much simpler way without any wires or soldering. That connector with the 6 used pins, pull it from the back of the speedo. Then you can see the pins exposed in the back of the speedo. The outside end pin of the group of 4 pins is the one to touch. Push it over to the side. Then put the 6 pin connector back over the other pins making sure the outside end pin stays bent out of the way and that the pin does not go back into the connector hole. That is all you have to do. This removes the rpm signal input so the oil warning board only looks for the lower pressure switch and doesn't care about the missing higher pressure switch. " Thanks, LDZ

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