Powertrain, generic · Vehicle speed, idle control and auxiliary inputs

P055B Engine Oil Pressure Sensor/Switch B Range/Performance

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

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.

Likely causes

Sensor B drifting or stuck
Sensor A wrong (comparison fails because of A)
Real pressure difference: clogged screen, oil level or quality
Contact resistance in the connector

Symptoms

  • Check engine light on
  • Cam phasing or valve lift switching possibly restricted
  • Often no noticeable symptoms

Repair estimate

DifficultyMediumDIY possible
Parts and labour€40–300
Time0.5–2 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

oil pressure sensor bsensor wiringengine control module

Related codes

P055AP055CP055DP0521P0011P0524

References: gsi.ext.gm.com, static.nhtsa.gov.