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  #1  
Old 03-05-2013, 08:15 AM
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Pegged Oil Pressure Gauge

The oil pressure gauge in my 190D with the 2.5 turbo instantly moves to the top of the scale as soon as the key is turned on. It shows full pressure before the engine even begins to turn.

Any ideas or suggestions on what could cause this? What can be done to fix it?

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1st MBz: 1982 300SD
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  #2  
Old 03-05-2013, 08:25 AM
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Oil Pressure Sensor wire has a bad connection or disconnected or the Oil Pressure Sensor is defective. There could be a problem somewhere else but these 2 things are the most common problem. I don't know exactly where the sensor is on your car but should be somewhere around the oil filter. If you ground the wire to the sensor with the ign on the gauge should read 0 psi. If it does then the circuit is good and it needs the sensor.

Paul
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  #3  
Old 03-05-2013, 08:47 AM
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Hmm

Quote:
Originally Posted by pmckechnie View Post
Oil Pressure Sensor wire has a bad connection or disconnected or the Oil Pressure Sensor is defective. There could be a problem somewhere else but these 2 things are the most common problem. I don't know exactly where the sensor is on your car but should be somewhere around the oil filter. If you ground the wire to the sensor with the ign on the gauge should read 0 psi. If it does then the circuit is good and it needs the sensor.

Paul
Oil pressure sensor wire disconnected = no reading = 0 bar.
Oil pressure sensor wire grounded = 3 bar.


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  #4  
Old 03-05-2013, 09:00 AM
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Thanks guys. As soon as the sun comes up I'll have a look under the hood.
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1st MBz: 1982 300SD
2nd MBz: 1987 300SDL
3rd MBz: 1995 S420
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  #5  
Old 03-05-2013, 09:25 AM
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Quote:
Originally Posted by whunter View Post
Oil pressure sensor wire disconnected = no reading = 0 bar.
Oil pressure sensor wire grounded = 3 bar.


.
Roy-
Is there a chance you got that reversed? When my oil pressure sensor recently failed in my w124, it demonstrated the opposite behavior. Unplugged caused it to peg at 3 bar.
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  #6  
Old 03-05-2013, 09:41 AM
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Answer

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Originally Posted by Shortsguy1 View Post
Roy-
Is there a chance you got that reversed? When my oil pressure sensor recently failed in my w124, it demonstrated the opposite behavior. Unplugged caused it to peg at 3 bar.
I will verify this, going out now to work on a w124.


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  #7  
Old 03-05-2013, 11:33 AM
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I think when you first turn on the key the Gauge is supposed to Peg out as a test just as the Warning lights also turn on when you first turn the Key.

Of coures once runinng the Gauges should return to normal.
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  #8  
Old 03-05-2013, 11:57 AM
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Quote:
Originally Posted by Diesel911 View Post
I think when you first turn on the key the Gauge is supposed to Peg out as a test just as the Warning lights also turn on when you first turn the Key.

Of coures once runinng the Gauges should return to normal.
none of my 124's do this... but once the car is started, the pressure climbs rapidly.
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  #9  
Old 03-05-2013, 01:18 PM
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Quote:
Originally Posted by Shortsguy1 View Post
Roy-
Is there a chance you got that reversed? When my oil pressure sensor recently failed in my w124, it demonstrated the opposite behavior. Unplugged caused it to peg at 3 bar.
I found the same thing.
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  #10  
Old 03-28-2022, 12:26 PM
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I had searched and this was the most aligned thread I could find.

My gauge on my 93 w124 300D is permanently pegged. Does this mean anything besides the fact that it is stuck?

I assume if it was a bad electrical issue we would be seeing it drop to zero at key off.

Key off and out:

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1991 350SD (206k)
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1996 Dodge Ram CTD (442k)
1996 Dodge Ram CTD (265k)

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1985 300D (233K)
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  #11  
Old 03-31-2022, 04:53 AM
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Answer

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Originally Posted by JHZR2 View Post
I had searched and this was the most aligned thread I could find.

My gauge on my 93 w124 300D is permanently pegged. Does this mean anything besides the fact that it is stuck?

I assume if it was a bad electrical issue we would be seeing it drop to zero at key off.

Key off and out:

Sounds like a bad sensor.

This link may help.

https://forums.mbclub.co.uk/threads/w124-oil-pressure-sensor-sender-testing.139491/
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  #12  
Old 03-31-2022, 07:44 AM
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Quote:
Originally Posted by whunter View Post
The odd thing is that the sensor stays pegged even with engine off key out.

I assume that itís normal spot is down/0, not fully pegged?
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Current Diesels:
1981 240D (73K)
1982 300CD (169k)
1991 350SD (113k)
1991 350SD (206k)
1991 300D (228k)
1993 300SD (291k)
1993 300D 2.5T (338k)
1996 Dodge Ram CTD (442k)
1996 Dodge Ram CTD (265k)

Past Diesels:
1983 300D (228K)
1985 300D (233K)
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  #13  
Old 03-31-2022, 08:33 AM
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Quote:
Originally Posted by JHZR2 View Post
The odd thing is that the sensor stays pegged even with engine off key out.

I assume that itís normal spot is down/0, not fully pegged?
The normal spot is down, but it still could be a bad sensor and a stuck gauge. If the sensor was bad and throws it to pegged, the needle might be stuck in that position. Try tapping the gauge cluster with the ignition off and see if the needle budges or falls to 0. If it pegs with the ignition on, but no engine running, the sensor is likely bad, or there is a wiring break in between.
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  #14  
Old 03-31-2022, 10:48 AM
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Quote:
Originally Posted by 87tdwagen View Post
The normal spot is down, but it still could be a bad sensor and a stuck gauge. If the sensor was bad and throws it to pegged, the needle might be stuck in that position. Try tapping the gauge cluster with the ignition off and see if the needle budges or falls to 0. If it pegs with the ignition on, but no engine running, the sensor is likely bad, or there is a wiring break in between.
Iíll try tapping more, or remove the cluster. It definitely never goes down, but I will have to see if say, itís permanently energized due to some voltage somewhere on the wire.
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Current Diesels:
1981 240D (73K)
1982 300CD (169k)
1991 350SD (113k)
1991 350SD (206k)
1991 300D (228k)
1993 300SD (291k)
1993 300D 2.5T (338k)
1996 Dodge Ram CTD (442k)
1996 Dodge Ram CTD (265k)

Past Diesels:
1983 300D (228K)
1985 300D (233K)
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  #15  
Old 03-31-2022, 12:10 PM
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What happens if you remove the battery? I.e. when there is no power. If it stays up then it is likely stuck gauge. If it goes to 0 then the wire to the gauge is short to chassis. I doubt it would be the sensor. Anyway I have a spare sensor if you need one. Cheap.

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