Faulty engine oil pressure sensor or switch 'B' sending an incorrect high signal; Damaged or shorted signal wire between the sensor and the engine control module; Corroded, loose, or contaminated sensor connector terminals; Sticking or failed oil pressure relief valve causing genuinely excessive oil pressure; Restricted oil passage or blocked oil filter bypass leading to high pressure at the sensor; Incorrect oil viscosity or overfilled crankcase raising measured pressure; Engine control module software calibration issue or internal driver fault

DTC codes / P05xx · Vehicle speed, idle control and auxiliary inputs / P055D

P055DEngine Oil Pressure Sensor/Switch B High

Q: What does code P055D mean?

Engine Oil Pressure Sensor/Switch B High. P055D indicates that the engine control module has detected an abnormally high signal from the 'B' engine oil pressure sensor or switch circuit, meaning the reported oil pressure is above the expected range for current operating conditions. The computer compares this input against a calibrated threshold and sets the code when the voltage or pressure reading stays too high for a defined period.

P055D indicates that the engine control module has detected an abnormally high signal from the 'B' engine oil pressure sensor or switch circuit, meaning the reported oil pressure is above the expected range for current operating conditions. The computer compares this input against a calibrated threshold and sets the code when the voltage or pressure reading stays too high for a defined period.

SystemPowertrain

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyIntermediate

AreaVehicle speed, idle control and auxiliary inputs

Symptoms you may notice

Illumination of the oil pressure warning light or a general engine warning light
Often no symptoms besides the warning light, especially if the fault is electrical rather than mechanical
Erratic or pegged oil pressure gauge reading on vehicles with a dash gauge
Audible valve train noise or ticking if actual oil pressure is genuinely too high
Oil leaks from seals or gaskets due to excessive pressure in severe cases
Reduced engine performance or limp mode if the module derates power for protection

Common causes, most likely first

Faulty engine oil pressure sensor or switch 'B' sending an incorrect high signal
Damaged or shorted signal wire between the sensor and the engine control module
Corroded, loose, or contaminated sensor connector terminals
Sticking or failed oil pressure relief valve causing genuinely excessive oil pressure
Restricted oil passage or blocked oil filter bypass leading to high pressure at the sensor
Incorrect oil viscosity or overfilled crankcase raising measured pressure
Engine control module software calibration issue or internal driver fault

How to diagnose and fix it

Verify oil level and condition, and confirm the correct viscosity is installed for the climate and engine
Inspect the sensor connector and wiring for chafing, corrosion, or a short to voltage, and repair as needed
Use a scan tool to read live oil pressure data and compare it with a mechanical gauge reading at the same port
Test the oil pressure sensor or switch 'B' circuit with a multimeter for reference voltage and signal return
Replace the oil pressure sensor or switch 'B' if electrical tests and mechanical gauge readings confirm a faulty sensor
Check the oil pressure relief valve and oil filter bypass for sticking or blockage if actual pressure is high
Clear the code and perform a road test to confirm the repair, rechecking live data for normal pressure range

What a high oil pressure reading really means

A high signal from the oil pressure sensor often comes from a short to voltage in the signal wire rather than a real mechanical pressure problem, so inspect the harness before condemning the sensor.
Some engines use a two-wire switch that only reports a yes/no pressure threshold, and a failed switch can report high pressure even when a mechanical gauge shows normal readings.
Genuine high oil pressure is frequently caused by a stuck pressure relief valve in the oil pump, which is easy to overlook when the sensor itself tests good.
After an oil change, overfilling the crankcase or using a much thicker oil than specified can push the sensor signal above the expected range and set this code.
A poor ground at the engine block can skew the sensor return voltage and mimic a high-pressure fault, so check ground straps before replacing parts.

Can I keep driving with P055D?

If the oil pressure warning light is on and you hear valve train noise, stop driving and have the vehicle towed to avoid engine damage. If the only symptom is the warning light and the engine sounds normal, you can drive cautiously to a repair shop but avoid high RPM and heavy loads until the cause is confirmed.

Tools that help

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Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.