Powertrain, generic · Fuel and air metering (injector circuit)

P023D Manifold Absolute Pressure - Turbocharger/Supercharger Boost Sensor A Correlation

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P023D compares the manifold pressure sensor (after the throttle) with boost sensor A (before the throttle): with the engine stopped both must read the same ambient pressure. Saab's 2.8 V6 checks this once per trip with the ignition on before starting and sets the code at a difference of more than 12 kPa, with the warning light and limp mode limited to 170 Nm. The code does not say which sensor is wrong – barometric pressure as a third value decides. Electrical faults of either sensor (P0107/P0108, P0237/P0238) block the test and must be fixed first. GM and Ford run the same comparison but report it as P0236, P0106 or P2227.

Likely causes

Manifold or boost sensor drifting or dirty
Contact resistance at connector or ground of one sensor
Pressure port or hose of one sensor blocked (oil sludge, ice)
Engine module or reference voltage

Symptoms

  • Check engine light on
  • Limp mode, limited power
  • Otherwise often unremarkable

Repair estimate

DifficultyEasyDIY 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

manifold absolute pressure sensorboost pressure sensor asensor wiring

Related codes

P0236P0106P0069P023EP2227

References: law.cornell.edu, saabwisonline.com, fordservicecontent.com, gsi.ext.gm.com.