P055BEngine Oil Pressure Sensor/Switch B Range/Performance
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Needs a drive cycle to confirm a fix
- How the car detects it
- Oil pressure sensor B is a second sensor, usually in the oil feed to the cam phasers or valve lift switching – on GM's 2.5 L (2014 Impala and Malibu) in the camshaft cover – while sensor A measures the main gallery. Documented only by GM (type B, two trips); Ford uses no sensor B. P055B compares sensors A and B with the phasers almost idle: GM sets it when they differ by more than 220 kPa below 1850 rpm, 80 of 100 samples. With the engine off, sensor B must read about atmospheric pressure (around 90 kPa); a GM bulletin for the 2014 2.5 L uses exactly that as a test. A real difference can also come from a clogged screen in the cylinder head feed.
- What you may notice
- Check engine light on
- Cam phasing or valve lift switching possibly restricted
- Often no noticeable symptoms
- Likely causes
- LikelySensor B drifting or stuck
- PossibleSensor A wrong (comparison fails because of A)
- PossibleReal pressure difference: clogged screen, oil level or quality
- RareContact resistance in the connector
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Often possible to do yourself.Typical cost: €40 – €300
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.