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

P055A Engine Oil Pressure Sensor/Switch B Circuit

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. P055A is the general circuit fault without low/high assignment. No manufacturer document available to us uses it – GM reports sensor B only as P055B–P055D. The module then uses a substitute value and may set cam phasers or valve lift to their base position.

Likely causes

Connector or harness to sensor B open, corroded or oily
Sensor B open internally
Shared 5 V reference or ground disturbed
Engine module

Symptoms

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

Repair estimate

DifficultyMediumDIY possible
Parts and labour€40–250
Time0.5–1.5 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

P055BP055CP055DP0520P0521P0641

References: gsi.ext.gm.com, static.nhtsa.gov, law.cornell.edu.