Powertrain, generic · Vehicle speed, idle control and auxiliary inputs
P055C Engine Oil Pressure Sensor/Switch B Low
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. P055C means the signal is too low – an open 5 V supply or signal line or a short to ground, not low oil pressure. GM sets it at a reading of 10 or less in 120 of 150 samples; real low pressure is P0524. The module uses a substitute value.
Likely causes
5 V supply or signal open, connector loose or corroded
Signal shorted to ground (chafing)
Sensor B faulty internally
Module's 5 V reference disturbed
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
References: gsi.ext.gm.com, static.nhtsa.gov.