This content was compiled automatically and has not yet been reviewed by a technician. For reference only.
For reference only. Always confirm part numbers and procedures for your specific vehicle.
Fault diagnosis
MG MG3 P0339: No engine speed signal found in the source case
The starter motor operates, but the engine does not start.
MG MG3 P0339: No engine speed signal found in the source case
Symptoms
- The starter motor operates, but the engine does not start. [1]
Diagnostic trouble codes
- P0339 (generic): No engine speed signal found in the source case [1]
Possible causes
- The source case found abnormal resistance in the crankshaft position sensor power supply wire; replacing the sensor did not resolve the problem. [1]
Checks
- Verify the reported code and starting symptoms, and check the sensor power supply, ground and wiring harness to the engine ECU. [1]
What to do
- Repair the power supply wiring confirmed to be abnormal and recheck; repairing the wiring resolved the fault in the source case. [1]
Applicability and limits
- Only applies to MG MG3; the source explicitly specifies model year 2012; only the vehicle described in case 3 is covered. Abnormal power supply wire resistance is the conclusion of that case and does not represent all P0339 cases. This case does not represent all models of the same brand; do not decide to replace parts based solely on the fault code. No vehicle model is currently linked. Scope: unknown [1]
- Only the vehicle described in case 3 is covered
- Abnormal power supply wire resistance is the conclusion of that case and does not represent all P0339 cases
Related part categories
- Engine wiring harness [1]
Sources
[Source 1] Casstime After-sales Technical Department: Xiaoma Classroom Repair Case 3 (2020-07-29) — Case 3: MG MG3, model year 12; symptoms and fault resolution (accessed 2026-11-01)
https://www.casstime.com/index/news/detail/id/1621.html
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