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

P0520 Engine Oil Pressure Sensor/Switch A Circuit

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. P0520 is the general circuit fault, used differently: Ford petrol and diesel engines set it for the digital SENT sensor when it reports an internal fault, does not initialise or sends values out of range (lost communication is U0600), after 5 s. GM's 1.4 L turbo with an oil pressure switch sets it when the switch reports pressure although the engine has been off long enough to be pressureless – type C, without warning lamp.

Likely causes

Sensor or switch faulty internally
Connector corroded or oily (oil creeping through a leaking sensor)
Signal line open or shorted to ground
5 V reference or supply faulty (usually with other sensor codes)

Symptoms

  • Check engine light (depending on the maker)
  • Oil pressure gauge or warning wrong
  • Cam phasing or cylinder deactivation possibly disabled

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.

What to check first

  1. Check oil level immediately
  2. Verify pressure with a mechanical gauge
  3. Inspect sensor wiring

Parts involved

oil pressure sensorsensor wiringengine control module

Related codes

P0521P0522P0523P0524P055F

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