P055B

Code

Generic P — Powertrain

Engine Oil Pressure Sensor/Switch B Range/Performance

Brand: Generic

Type: P — Powertrain

Views: UK: 18 EN: 39 RU: 27

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Faulty oil pressure sensor/switch (Sensor B)
Open, short to ground, or short to battery in sensor wiring or connector
Corroded, loose, or damaged sensor connector pins
Low engine oil level or incorrect oil viscosity
Restricted or failing oil pump / relief valve or internal engine oil passage blockages
PCM/ECM internal fault or poor ground at control module

Read and record all stored DTCs and freeze-frame/live data
Check engine oil level and condition (contamination, viscosity)
Visually inspect sensor body, connector, and wiring for damage or oil intrusion
Backprobe sensor connector and observe signal while cranking and at idle using a scan tool or multimeter
Check PCM reference voltage (typically ~5 V) and sensor ground continuity
Wiggle test harness while monitoring live data for intermittent faults

Typical oil pressure sensor systems use a 5 V reference and return a 0–5 V signal to the PCM (manufacturer-specific)
Typical sensor output examples (generic): ~0.5 V at ~0 psi, 2.0–3.5 V at normal operating pressure, up to ~4.5 V at high pressure (values vary by vehicle)
Direct mechanical oil pressure range commonly 0–100 psi (0–7 bar) depending on engine
If sensor is resistive type, resistance will change with pressure — consult OEM chart for exact ohms vs pressure

Connect a full-function scan tool; record freeze-frame data and confirm P055B is current or stored.
Verify engine oil level and condition; correct oil level and viscosity if needed, clear code and retest.
Visually inspect sensor, connector, and harness for contamination, corrosion, bent pins, or damage.
Backprobe sensor with vehicle at key-on engine-off: check for stable reference voltage from PCM (≈5 V) and a good ground.
Start engine and monitor live sensor voltage/pressure data; rev engine — voltage should change smoothly with oil pressure. Note any erratic or out-of-range readings.
Perform wiggle test on wiring and connector while monitoring live data to reveal intermittent faults.
Measure sensor resistance or output against OEM specification; if out of range, replace sensor.
If wiring shows open/short or no reference voltage, trace and repair harness or connector; repair grounds and retest.
If electrical tests are good but readings remain abnormal, perform a direct mechanical oil pressure test with a calibrated gauge to confirm actual oil pressure and diagnose pump/relief valve issues.
If sensor, wiring, and mechanical pressure are correct, consider PCM diagnosis or replacement as last resort.