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

P0523 Engine Oil Pressure Sensor/Switch A High

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

The oil pressure sensor matters for emissions control because modern engines use it as an input – for two-stage or regulated oil pumps, hydraulic cam phasers and GM's cylinder deactivation, whose lifters switch by oil pressure. P0523 means the signal voltage is above its limit: GM 2018 above 95 % of the 5 V reference, GM 2006 above 4.89 V, Ford petrol above 4.75 V, Ford diesel above 4.992 V, about 5 s. Typical are an open sensor ground or a signal shorted to 5 V or battery voltage. Real excess pressure is not reported here – Ford uses P055F for that. GM's 2006 V8s used the warning lamp only with cylinder deactivation.

Likely causes

Sensor ground open
Signal shorted to 5 V reference or battery voltage
Sensor faulty internally
Oil or moisture in the connector

Symptoms

  • Check engine light (depending on the maker)
  • Oil pressure gauge at maximum
  • Cam phasing or cylinder deactivation possibly restricted

Repair estimate

DifficultyEasyDIY possible
Parts and labour€50–250
Time0.3–1.5 h

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

Parts involved

oil pressure sensorsensor wiringengine control module

Related codes

P0520P0521P0522P0524P055F

References: gsi.ext.gm.com, gsi.ext.gm.com, fordservicecontent.com, fordservicecontent.com.