Powertrain, generic (extended)

P235A Cylinder 10 Pressure Variation High

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

P235A is the counterpart to P2359: the cylinder 10 pressure signal swings more than the combustion can explain, with spikes or steps from one cycle to the next. A public manufacturer description of this tenth-cylinder code does not exist. In the Saab 9-5 diesel the cylinder-1 version P039D belongs to the signal performance group; it is Type B and responds within 0.2 s of leaving its window. Electrical noise is the usual reason: a signal wire with damaged shielding or chafed insulation, a poor engine ground, or unstable sensor electronics. Genuinely irregular combustion is rarer, for instance when an injector dribbles after closing. VW's TDI bulletin recommends watching the maximum pressure reading while flexing the harness – jumps then betray the wiring. The warning lamp is mostly the only sign.

Likely causes

Interference on a damaged or poorly shielded signal wire
Poor engine ground or corroded ground point
Sensor electronics delivering an unstable signal
Injector dribbling after closing, combustion varies

Symptoms

  • Check engine light on
  • Usually no noticeable symptoms

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€80–550
Time1–3.5 h

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

Parts involved

cylinder pressure sensor glow plugsensor wiringengine control modulefuel injector

Related codes

P2359P2356P2353P2350P2364P039D

References: saabwisonline.com, static.nhtsa.gov, law.cornell.edu.