help asap outta town oil light keeps coming on
Senior Member
Joined: Jul 2012
Posts: 8,999
From: C-Town
The PCM detects that the oil pressure switch signal circuit is high
Inside the oil pressure switch is a pressure-sensing device that’s in direct contact with the oil flow. Oil pressure can either increase or decrease the sensor’s resistance and the PCM is capable of converting these changes into an accurate interpretation of the actual oil pressure.In other words, the oil pressure sensor that triggers a P0520 code is typically a three-wire sensor with 5 volts, a signal return ground, and a signal voltage that varies with engine oil pressure. The sensor’s job is to convert engine oil pressure to a voltage reading that the ECM/PCM is programmed to interpret as an accurate indicator of engine oil pressure.
A working pressure sensor will output a voltage within an upper and lower voltage limit. The lower threshold is purposely greater than 0V so that a circuit check can be performed on the device. If the PCM determines the sensor voltage is outside the ideal threshold for a period of time, the sensor’s signal is deemed invalid and code P0520 is set.
Thread Starter
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Senior Member
Joined: Feb 2023
Posts: 111
The PCM detects that the oil pressure switch signal circuit is high
Inside the oil pressure switch is a pressure-sensing device that’s in direct contact with the oil flow. Oil pressure can either increase or decrease the sensor’s resistance and the PCM is capable of converting these changes into an accurate interpretation of the actual oil pressure.In other words, the oil pressure sensor that triggers a P0520 code is typically a three-wire sensor with 5 volts, a signal return ground, and a signal voltage that varies with engine oil pressure. The sensor’s job is to convert engine oil pressure to a voltage reading that the ECM/PCM is programmed to interpret as an accurate indicator of engine oil pressure.
A working pressure sensor will output a voltage within an upper and lower voltage limit. The lower threshold is purposely greater than 0V so that a circuit check can be performed on the device. If the PCM determines the sensor voltage is outside the ideal threshold for a period of time, the sensor’s signal is deemed invalid and code P0520 is set.
Senior Member
Joined: Jul 2012
Posts: 8,999
From: C-Town
Change engine oil & filter with the recommended above & clear code, then drive on. No further action required at this time.
Super Moderator
Joined: Jul 2007
Posts: 13,090
From: Boat Town USA MI
It should be safe to drive as long as the oil is at the proper level, is amber to gold, the engine sounds normal and is operating at normal temperature. Which means is if you want help, then answer the questions posed directly.
You might want to trace the wiring harness to the OPS to make sure it has not rubbed on something or otherwise compromised the harness insulation looking for cracks and heat damage as well.
You might want to trace the wiring harness to the OPS to make sure it has not rubbed on something or otherwise compromised the harness insulation looking for cracks and heat damage as well.
Thread Starter
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Senior Member
Joined: Feb 2023
Posts: 111
It should be safe to drive as long as the oil is at the proper level, is amber to gold, the engine sounds normal and is operating at normal temperature. Which means is if you want help, then answer the questions posed directly.
You might want to trace the wiring harness to the OPS to make sure it has not rubbed on something or otherwise compromised the harness insulation looking for cracks and heat damage as well.
You might want to trace the wiring harness to the OPS to make sure it has not rubbed on something or otherwise compromised the harness insulation looking for cracks and heat damage as well.
Senior Member
Joined: Jul 2012
Posts: 8,999
From: C-Town
Just to recap:
You started this thread with "oil light on at idle" (=low oil pressure/blockage passageways)
You added seafoam & "drove 150miles no oil light on until, you parked, light on with higher rpms, off at idle", and you have a code p0520.
The PCM detects the signal from the OPS is out of range, which can be caused by improper oil viscosity.
Start there and post an update.
You started this thread with "oil light on at idle" (=low oil pressure/blockage passageways)
You added seafoam & "drove 150miles no oil light on until, you parked, light on with higher rpms, off at idle", and you have a code p0520.
The PCM detects the signal from the OPS is out of range, which can be caused by improper oil viscosity.
Start there and post an update.
Thread Starter
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Senior Member
Joined: Feb 2023
Posts: 111
Update so after I did motor oil flush at 300 miles and replaced with acdelco filter and Mobil one oil still was doing same thing,oil light it’s staying steady so I replaced the oil sending unit. still oil light stays on so i ordered oe gm oil sending unit went 15 miles down road, came home still same thing. at this point Mechanic said motor gone or one last shot. I also order pigtail the oil sending unit plug to get it replaced. honestly I’ve put a lot in this hummer barely been 2 months I’m kinda burnt out. I love it but experience so far is been honest a nightmare
Senior Member
Joined: Sep 2008
Posts: 6,126
From: SE Michigan
Update so after I did motor oil flush at 300 miles and replaced with acdelco filter and Mobil one oil still was doing same thing,oil light it’s staying steady so I replaced the oil sending unit. still oil light stays on so i ordered oe gm oil sending unit went 15 miles down road, came home still same thing. at this point Mechanic said motor gone or one last shot. I also order pigtail the oil sending unit plug to get it replaced. honestly I’ve put a lot in this hummer barely been 2 months I’m kinda burnt out. I love it but experience so far is been honest a nightmare
Any oil pressure readings? OBDII vs actual pressure gauge readings?