What it means
Engine Oil Pressure Sensor or Switch B Circuit: an electrical fault is present in the circuit.
At a glance
- Usually lights the check-engine light
How it works
Engine oil pressure sensor or switch B provides an electrical signal the control module uses to monitor oil pressure. P055A indicates an electrical fault in that B circuit; it does not tell you whether actual oil pressure is low, so an oil warning or engine noise needs immediate attention.
Common causes
Most likely first.
- Oil pressure sensor or switch B failed
- Open or short in sensor wiring
- Loose, corroded, or damaged connector
- Engine oil level or pressure problem
Symptoms
- Check-engine light may come on
- Oil pressure warning light may come on
- Oil pressure gauge or display may be erratic
- Engine noise if oil pressure is actually low
How to diagnose it
- Check the oil level and look for an oil-pressure warning or engine noise before running the engine further.
- Use a scan tool to record freeze-frame data and compare the sensor B reading with other oil-pressure information, if available.
- Locate the vehicle-specific sensor or switch B and inspect its connector and wiring for looseness, corrosion, damage, or oil contamination.
- Test the B circuit for opens, shorts, and poor connections against the manufacturer's specification.
- If the circuit checks out, test sensor or switch B and verify actual oil pressure using the manufacturer's specified method.
Common fixes
- Correct the oil level if it is low, using the specified oil.
- Clean and secure the sensor B connector.
- Repair damaged or open wiring in the B circuit.
- Replace sensor or switch B if it fails testing.
- Address any confirmed mechanical oil-pressure problem before continued operation.
Can I keep driving?
If the oil-pressure warning is on, the engine is noisy, or the gauge reads dangerously low, shut off the engine and do not drive; low oil pressure can quickly damage it. If there are no such signs, limit driving and arrange prompt diagnosis because the warning signal may be unreliable.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.