Powertrain, generic (extended)

P235E Cylinder 11 Pressure Sensor Circuit Low

Check engine lightOn

EmissionsRelevant

Drive cycleRequired

Limp modeNo

With P235E the signal of the cylinder 11 combustion pressure sensor is too low, typically close to zero. No manufacturer documents this code, as twelve-cylinder engines with pressure sensors are not described publicly; the analogue is P0397 for cylinder 1 in Saab's 9-5 diesel, where a low signal must persist beyond 2 s with the engine running before the Type B code is logged. The first check there concerns the supply: 4.8 to 5.2 V on the reference terminal with ignition on; less voltage means the reference is interrupted or shorted to ground. Across reference and low reference of the plug itself, 3 to 12 Ohm are expected. A signal wire chafed through to the cylinder head also drags the input down. With bank-wise numbering the plug sits between cylinders 10 and 12, so their harness branches deserve a look too.

Likely causes

5 V reference interrupted or shorted to ground

Signal wire chafed through to ground

Sensor glow plug outside its 3–12 Ohm specification

Symptoms

Warning lamp after the second faulty trip
Peak pressure of cylinder 11 shown as zero

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.