Powertrain, generic · Ignition system or misfire

P03D9 Cylinder 7 Pressure Variation High

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

Some diesels have a combustion pressure sensor in the glow plug; the engine module uses it to control injection for each cylinder. This code concerns cylinder 7. P03D9 means the swing of the pressure signal is too large. The only manufacturer we found using this code family, GM's European 2.0 CDTI four-cylinder diesel (Saab 9-5, 2010), uses 'pressure variation too high' for cylinders 1 to 4: signal outside its range for more than 0.2 s with the engine running; what exactly is measured, Saab does not explain – presumably a noisy or overshooting signal, from faulty sensor electronics, interference or a combustion anomaly. For cylinder 7, which only engines with at least 7 cylinders have, no manufacturer document available to us uses the code; the description follows that logic and CARB. Usually there are no noticeable symptoms.

Likely causes

Sensor in the glow plug faulty (signal noise)
Loose contact or interference on the signal wire
Combustion anomaly (dripping injector, harsh combustion)

Symptoms

  • Check engine light on
  • Usually no noticeable symptoms
  • Possibly rough running or combustion noise because control is off

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€100–450
Time1–3 h

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

Parts involved

cylinder pressure sensor glow plugsensor wiringengine control module

Related codes

P03D8P03D5P03D2P039DP03A7

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