P2349 is the plausibility code for the combustion pressure sensor of cylinder 9: the signal is electrically valid but does not match what the ECM expects for the operating point. CARB requires input sensors to be checked for rationality where feasible, in both directions. A natural test point is overrun, when no fuel burns and the peak pressure should match the pure compression pressure; GM's European diesel in the Saab 9-5 already uses that peak to locate top dead centre. No manufacturer publishes this cylinder-9 code; its counterpart for cylinder 1 is P0396. Likely causes are carbon on the sensing element, a leaking glow plug seat or a plug fitted with the wrong torque, which detunes the sensor. The ECM ignores the signal, and the driver hardly notices anything.
Medium severity. Can I keep driving?If the car is running normally, drive in moderation to a repair shop. If it loses power or another warning appears, do not continue.
Cylinder 9 is numbered according to the manufacturer: check your engine's manual before working on it.
Symptoms
- Check engine light on
- Usually no noticeable driveability change
Most likely causes
- Sensor drift from combustion deposits
- Glow plug seat leaking or plug tightened to wrong torque
- Genuinely low compression in cylinder 9 distorting the comparison
What to check, in order
Start with the simplest. You can tick off each step.
Good to know
- Repair difficulty: medium
- It affects emissions.
What each character of P2349 means
- P: Powertrain: engine and transmission
- 2: Generic code: same on every make
- 3: Ignition and misfires
- 49: Specific fault in that system
Frequently asked questions
Can I keep driving with code P2349?
If the car is running normally, drive in moderation to a repair shop. If it loses power or another warning appears, do not continue.
What causes code P2349?
The most common causes are: sensor drift from combustion deposits; glow plug seat leaking or plug tightened to wrong torque; genuinely low compression in cylinder 9 distorting the comparison.
Related codes
- P2348Cylinder 9 Pressure Sensor Circuit
- P234ACylinder 9 Pressure Sensor Circuit Low
- P234BCylinder 9 Pressure Sensor Circuit High
- P234DCylinder 9 Pressure Too Low
- P0396Cylinder 1 Pressure Sensor Circuit Range/Performance
- P2353Cylinder 10 Pressure Sensor Circuit Range/Performance
Sources
- law.cornell.edu: 13 CCR 1968.2
- borgwarner.com: pressure sensor glow plugs
- saabwisonline.com: dtc p0399 p039c p039d p03a3 p03a6 p03a7 p03ad p03b
Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.