Oil Pressure Problem? Troubleshooting Guide.

Hello everyone,

'Since I'm new to the forum, hello everyone! I hope you can help me. Recently, the oil warning light has been flashing, and a warning sound is coming from the instrument cluster. This always happens at around 2100 rpm. Initially, it only occurred sporadically and at higher speeds (around 4000 rpm). Since I have an oil pressure gauge, here are some readings.'
Oil pressure sensor on the oil filter housing:
Engine cold, idle pressure 3 bar.
Engine hot, idle pressure 0.9 bar.

Oil pressure sensor on the cylinder head:
Engine cold, idle pressure 2.5 bar.
Engine hot, idle pressure 0.6 bar.

Overall, the oil pressure decreases as the oil temperature increases, according to the display. For example, at 2100 rpm, I only have 0.9 bar of oil pressure, and under full load, the maximum reading is 1.5 bar, according to the gauge located on the cylinder head.

'At the workshop, the original oil pressure sensor was replaced, but there was no change. The wiring harness was bypassed due to suspicion of a broken wire, but still no change. A different instrument cluster was also tried, with no change.'

Okay, so my question is: Is the oil pressure too low, and what could be causing that? What else could trigger the warning sound? Could it possibly be a defective oil level sensor? Do those even exist?

Here are the vehicle details: Seat Ibiza GT TDI, manufactured in June 1998, engine code AFN, mileage 173,400 km. The oil is 5W40, and since the last service at 165,000 km, the oil consumption has been 0.1 liters (requiring a top-up).

Best regards, Boro.

Hello,

At a temperature of 80°C and an engine speed of approximately 2000 RPM, the oil pressure must reach at least 2 bar.

If I understand correctly, the workshop didn't perform an oil pressure test using a gauge, but only suspected electrical problems?

I wouldn't move the car if I were you (a major engine failure is likely).


To verify:
- Is the oil filter okay?
- Is the oil pump and the strainer in good condition?
Have you ever experienced engine damage caused by excessive contamination entering the engine oil?


PS: If the oil warning light comes on, I would advise you to take it more seriously and not immediately look for electrical problems (especially if you have an oil pressure gauge). When encountering such errors, always rule out all possible mechanical causes first.
How many kilometers have you driven since the first warning?

Sure, here is the translation of the text from German to English:

'Hi Michael II,'

To my shame, I have to admit that I've already driven about 6000 km since the first time this happened. It wasn't like I didn't care! The oil pressure reading on the display hadn't changed compared to before. The sensor was still attached to the oil filter housing. Of course, I went straight to the workshop. At that time, I was on my way to the Baltic Sea and basically stopped at a car dealership in an unfamiliar town. They didn't measure the oil pressure there, but simply checked if oil was still reaching the cylinder head and tried to read the error memory. Naturally, there was nothing stored because the instrument cluster isn't yet capable of diagnostics.

'What surprises me is that the oil pressure at the oil filter housing hasn't changed from what it was before, when there were no alarms. Now I've installed the original sensor from the cylinder head on the oil filter housing, and yet the alarm is still triggered, even though the initial pressure here is 1. the same as before and 2. higher than at the Z-head, which should definitely be within the acceptable range! That's why I thought the source of the problem might be somewhere else. So far, I haven't had any major technical problems with the car or engine. The only issue was a broken cable to the fuel injection start valve on the ESP.'

But I think I'm going to get the filter and oil changed, and while they're at it, have them check the intake area of the pump!

Hello,

'I'm experiencing a similar problem. When my engine gets warm, it starts to trigger an alarm around 1500 RPM. I've already replaced the oil pressure sensor three times, but there's no change. I've also had an oil change, and the error memory doesn't show anything.'

'The amazing thing about this speed is that when you're driving on a country road behind a truck, there's constant beeping and flashing inside the car. =('


Best regards, Andy.

Hello Andy,

What values does the pressure gauge test show?

Well, Andy,

'That beeping really annoyed me, so I removed the fuse first! That stopped the beeping, but also disabled the display in the instrument cluster, and I drove 400 km without the speedometer working! Option number two: let it beep and turn up the radio to maximum! The result? After 200 km on the highway, you get out feeling exactly like you've had 10 beers! Right now, I've removed the oil light and taped over the horn in the instrument cluster. Now there's no more beeping or blinking!'

It might not be the most elegant English, but I'm pretty sure there's an electrical fault with mine! So, I'll have to start troubleshooting it sometime.

Best regards, Boro.

Boro wrote:
"At the workshop, the original oil pressure sensor was replaced, but there was no change. The wiring harness was bypassed due to suspicion of a broken wire, but still no change. Trying a different combination instrument also resulted in no change."


What's left then, other than a great electrical gremlin?! *wonder* It seems you're handling it quite carelessly. I wonder if that's the right approach... I would also follow Michael II's advice and first check for mechanical causes. After all, every vehicle has specified oil pressure values - Michael mentioned 2 bar - And I think there was a reason for that. What exactly are you expecting here?! You receive a very good tip about a risky problem, and then you describe how to disable the light and silence the buzzer. So, in essence, this thread is now over, isn't it?!


Best regards,
pretzel

Hi Pretzel,

"Thank you! That's exactly my opinion!"

"Quote:"

... because they don't know what they're doing ...

"Quote End"

'Oops, sorry if I offended anyone! But to answer your question, I was hoping to find more possible causes for the problem and maybe connect with people who have had similar issues. First of all, I'm not entirely sure what else besides oil pressure can trigger the alarm. Is there an oil level warning system? Regarding the carelessness comment, of course, I wouldn't risk damaging my engine lightly, and that's why I took it to a workshop! The master mechanic in Rostock said: 'Oil is still being pumped up, you need to have your local garage investigate where the problem lies. We once spent a week searching for a broken cable in an Arosa... etc.! That was the end of the diagnosis. So much for the expertise of a workshop, and since I'm from Thuringia, I had a 500 km drive home! Unfortunately, my local garage isn't any better, but at least they use a manual for the AFN engine when troubleshooting. You can imagine that nothing really comes out of it except high hourly rates! Not even the oil pressure at the head was measured electronically! The only reason I kept driving was that, according to the display, the values with the alarm hadn't changed, meaning they were exactly the same as before. By the way, the gauge came from a salvaged gasoline car, goes up to 5 bar, and has a VDO sensor for 0-10 bar. I'm not even sure if it's displaying the correct values. The warning used to appear sporadically, then disappeared completely for a while, and then reappeared after 1500 km following an inspection and oil change. Since I want to get rid of this problem once and for all, I posted here.'

Hello,

That means you're not sure what kind of values your "treasure" is providing. And yet, you haven't done anything else besides tinkering with the electrical components.

I already wrote this above, but I'm happy to repeat it if you like:

"1. Have the oil pressure checked using a mechanical, calibrated gauge (every reputable workshop should have one)."

If the values are below the target value (2 bar overpressure at a minimum oil temperature of 80°C and a minimum speed of 200 RPM), we proceed to point 2.

2. Check the oil pump and oil filter (the pressure relief valve may be opening too early).

If the values are within or above the target value:
- Continue searching for the causes calmly, as there is no immediate engine failure risk.

Michael II wrote:

If the values are below the target value (2 bar overpressure at a minimum oil temperature of 80°C and a minimum speed of 200 RPM), we proceed to point 2:

... I'll add this: 2000 RPM (the engine definitely won't run at 200).

Hi,

I drive the same car and had the same problem.
The annoying beeping sound occurred sporadically over approximately 50,000 kilometers when the engine was warm.
More and more frequently, towards the end. Workshop opinions ranged from a cracked plate to engine damage. However, I didn't have anything repaired because I thought that if the oil pressure is high enough at idle, it should always be sufficient at 2000 rpm. Now I discovered that the connector on the oil pressure sensor (located under the rubber cap on the oil filter) was extremely loose. Apparently, the connector expands when the engine is hot, and under certain vibrations, the contact becomes insufficient.
The plug was bent with pliers and inserted, and it's been fine for 3000 km!

Quote:

By the way, the gauge comes from a gasoline engine and goes up to 5 bar, and it has a VDO sensor that measures from 0 to 10 bar.

Hello,

Okay, here's the translation:

"Then, this thing will display exactly half of the actual oil pressure. The sensor outputs a signal for full scale at 10 bar, but the instrument then shows 5 bar. If it displays 0.9 bar, the actual pressure is 1.8 bar. If you have a sensor with an additional warning contact (i.e., one with two connections), remove it and check what numbers are printed on the key surfaces. Gasoline engines start complaining at much higher oil pressures than the standard pressure switches used in diesel engines (e.g., 1.5 bar instead of 0.9 bar). Also, keep in mind that the pressure switch on the oil filter is a "normally closed" type, while the one on the camshaft is a "normally open" type. This means that if you connect the sensor from the oil filter gauge to the camshaft and also connect the cable from the pressure switch, the device will start beeping as soon as there's pressure. Your problem seems to be electrical in nature."

Best regards, Uli[/quote]

The problem has now been fixed! I took the car to another workshop and had the oil pressure checked at the cylinder head. Everything was fine! They also replaced the oil pressure sensor again. Since then, it's gone.