Ahsai

Mine sits at 0.5bar but I thought it used to be at 0. I think the sensor is failing. A tech from the dealer said it's residual pressure in the system and the sensor is correct. I think it's BS. What do you think?

Kazual99

How long after the engine is shut off are you taking the reading?

Ahsai

From immediately after to letting the car sit overnight. Didn't make a difference at all. I think it used to read 0 whenever engine was OFF...

SSST

Mine goes to 1/2 bar if overnight, and 0 if it has been sitting for a few days. I'm not an expert, but your tech may be right.

Ahsai

Thanks! That is interesting. I'll check if mine behaves the same too.

02TX996Cab

Having the sensor possibly "failing high" is not a good thing...the real pressure could drop to nil but the sensor might not give a warning if it is reading high. Result--blown engine. IMHO, the cost of replacing the sensor is well worth ensuring one has accurate oil pressure readings. That's not a risk I'd personally take.

First thing I'd do is clean the two contacts on the sensor. If the residual pressure reading persists, I'd spend the $50 for the part and an hour of my DIY time to replace the sensor and eliminate the risk of a "going bad" sensor. This is less expensive than my tech putting in a parallel shop oil pressure gauge to verify the reading of the normal gage.

Based on my experience, residual oil pressure after shutting the engine off for any reasonable length of time is zero...so I'd vote "bad sensor" in your case. But even if my guess turns out wrong I'd still replace the sensor to be 100% certain and have peace of mind.

Good luck.

Ahsai

Can't agree more. I also do not see how there's any residual oil pressure. My sensor is likely failing anyway since it dropped to zero momentarily the other day and the "Oil indicator" error msg popped up briefly and was gone before I had a chance to pull over. I did pull over and restart the car and everything was normal. This is already my 2nd sensor (1st one failed in 3 yrs) and this one is also 3 yrs old. So looks like they fail every 3 years

Ahmet

The sensor is likely failing however I believe the low oil pressure "switch" is separate internally. If your oil light comes on w/the ignition on but engine not running, the warning system is active. This means that in the event of oil pressure loss, the MK1 cars it should at least turn on the warning light and on the MK2 cars it should sound the beep, turn the instrument cluster red w/the symbol/message "low oil pressure" as well as illuminate the low oil pressure warning light.

Ahsai

Ok. Got the sensor replaced today and the pressure gauge reads exactly "0" when key ON engine OFF. It's repeatable over and over again even when I turn off and on the engine.

So the conclusion is our oil pressure gauge should read "0". If not, it is failing or marginal. Mine read "0.5" before replacement and I got the oil pressure indicator failure warning with mometary 0 oil pressure at highway speed. Also, the residual pressure theory is BS.

silotwo

Ditto - I had the exact same symptoms about one month ago, 25 months after I had the first one replaced- dealer confirmed gauge should be at zero bars - mine read .05, had the momentary warning and gauge dropped to zero. $112.00 parts and labor at the dealer. If only I ever had a repair that cheap on my oldsmobile.

Blue Chip

Interesting. After my engine swap (the new is known to be good) - the oil pressure seemed to be reading .5bar lower than it should. I am getting .5bar at key on / engine off. I'm having it static tested next week - but have heard it could be either the sensor or the instrument cluster.

Since I am experiencing speedo and fuel level issues as well - I'm not ruling anything out.

RSBro

After my most recent service, my oil pressure readings have been weird and giving faults, but only if it's been sitting for a while and I drive 'briskly' without letting the car warm up first. It's happened twice, so not repeatable or often, but it happened this morning and the indicator would go up to 5 and stick, then down to 0 and stick, few times of doing that, then after about 7 mins settled in the middle where it usually is... .weird.

beetleything

Good to know - Thanks.

Porschetech3

The oil pressure sensor has a diaphragm and spring, also with along with a sliding resister contact and a warning contact. Sometimes the sliding resister can loose contact, or the diaphragm sticks and causes false readings. It also has a PTFE vent in between the electrical contacts to vent the diaphragm area that can get stopped up with dirt and cause false readings. Overall not the most reliable sensor I have ever seen.



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