P055B: Engine Oil Pressure Sensor/Switch B Circuit Range/Performance

What it means

Same as P055A with the signal in plausible range yet not matching the engine model.

At a glance

• Usually lights the check-engine light

How it works

Engine oil pressure sensor or switch B reports pressure to the control module, which checks whether the reading follows the expected pattern as the engine operates. P055B sets when the B signal is electrically plausible but does not match that pattern, which can result from a drifting sensor, oil condition, or restricted oil flow.

Common causes

Most likely first.

1. Oil pressure sensor or switch B worn or drifting
2. Oil level or oil condition affecting pressure
3. Restricted oil filter or oil passage
4. Connector or wiring fault

Symptoms

• Check-engine light may come on
• Oil pressure reading may fluctuate or seem inaccurate
• Oil pressure warning light may come on
• Engine noise if pressure is outside the safe range

How to diagnose it

1. Check the oil level, condition, and service history, and note any oil-pressure warning or engine noise.
2. Record freeze-frame data and observe the sensor B reading in live data as the engine warms and operating conditions change.
3. Inspect the B sensor connector and wiring for corrosion, looseness, damage, or intermittent contact.
4. Check that the oil filter and oil passages are not restricted, using the vehicle's specified service information.
5. If the reading still appears implausible, test actual oil pressure and sensor B against the manufacturer's specification.

Common fixes

• Correct the oil level and use oil that meets the vehicle specification.
• Replace an overdue or restricted oil filter.
• Repair a loose connector or damaged wiring to sensor B.
• Replace sensor or switch B if it drifts or fails testing.
• Repair a confirmed restriction or mechanical oil-pressure fault.

Can I keep driving?

If the oil-pressure warning stays on, the engine is noisy, or the reading is very low, shut the engine off and do not drive; damage can occur quickly. Otherwise, keep driving to a minimum until actual pressure is verified.