Powertrain, generic (extended)

P235F Cylinder 11 Pressure Sensor Circuit High

Check engine lightOn

EmissionsRelevant

Drive cycleRequired

Limp modeNo

P235F is logged when the cylinder 11 pressure sensor signal remains above its plausible maximum. Only twelve-cylinder engines have this cylinder, and no maker documents the code; the Saab 9-5 diesel serves as the model with P0398 for cylinder 1, a Type B code that needs more than 2 s over the threshold. In that wiring layout three faults produce a high reading: an open low reference, an open signal wire and a reference or signal shorted to battery voltage. Saab's test plan therefore measures less than 5 Ohm between the low reference and ground, and it requires infinite resistance between every sensor terminal and the plug body – broken insulation inside the glow plug would also distort the signal. The cylinder runs on without pressure feedback; P235E is the opposite case.

Likely causes

Low reference (ground) wire of the sensor open

Signal wire interrupted or connector off

Reference or signal shorted to battery voltage

Insulation failure between sensor terminals and plug body

Symptoms

Check engine light after two trips
Implausibly high fixed pressure value for cylinder 11

Repair estimate

DifficultyMediumWorkshop job

Parts and labour€50–500

Time0.5–3.5 h

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

Parts involved

cylinder pressure sensor glow plugsensor wiringengine control module

References: saabwisonline.com, law.cornell.edu.