P055B code meaning
Engine Oil Pressure Sensor/Switch B Range/Performance
Powertrain system Generic code P05xx codes Check engine light
What P055B means
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.
P055B at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modeNot expected
- Repair difficultyMedium, DIY possible
- Typical labor0.5 to 2 hours
- Clears after repairAfter a drive cycle
Symptoms of P055B
- Check engine light on
- Cam phasing or valve lift switching possibly restricted
- Often no noticeable symptoms
Common causes of P055B
- Most likelySensor B drifting or stuck
- PossibleSensor A wrong (comparison fails because of A)
- PossibleReal pressure difference: clogged screen, oil level or quality
- Less likelyContact resistance in the connector
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Oil pressure sensor bSensor wiringEngine control module
What each part of P055B means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 5 | Area: vehicle speed, idle control and auxiliary inputs. |
| 5B | The exact fault in that area. |
What to do next
- Note P055B and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P055B
What does P055B mean?
P055B means "Engine Oil Pressure Sensor/Switch B Range/Performance". 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. It is a generic code, so it means the same on every make.
Is it safe to drive with P055B?
Usually yes, for a short time, if the check engine light is steady and the car drives normally. If the light flashes or the car runs badly, stop and have it checked.
Will P055B fail an emissions test?
Yes, it can. P055B is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P055B to fix?
Difficulty: medium. A typical repair takes 0.5 to 2 hours of work. A careful DIY repair is possible with basic tools and a scanner.
Will P055B clear itself after the repair?
After the repair the car has to complete a drive cycle (a mix of city and highway driving) before the test runs again. Until then the readiness monitor shows "not ready", which can fail an inspection.