P1357 is a manufacturer-specific OBD-II diagnostic trouble code. Its exact definition depends entirely on the vehicle application, ranging from ignition diagnostic monitor faults to specific cylinder misfires.
The exact application must be verified before diagnosis. The code indicates the control module detected an ignition system or misfire fault, but testing is required to identify the root cause.
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Key Takeaways
- P1357 is a manufacturer-specific code, meaning its exact definition varies by automaker and vehicle application.
- On Ford applications, it indicates an Ignition Diagnostic Monitor (IDM) pulsewidth or circuit fault.
- On BMW applications, it indicates a misfire with fuel cut-off on a specific cylinder.
- Diagnosis requires verifying the exact factory definition and testing the relevant ignition or misfire components.
P1357 Code Description and Implications
P1357 is a manufacturer-specific powertrain code. Because the second digit is “1”, the definition is controlled by the automaker rather than the SAE standardized list.
Some Ford applications: P1357 indicates an Ignition Diagnostic Monitor (IDM) pulsewidth not defined fault, meaning the powertrain control module cannot determine the ignition coil pulsewidth signal.
Some BMW applications: P1357 indicates a misfire with fuel cut-off on Cylinder 8, meaning the control module detected incomplete combustion and disabled the fuel injector to protect the catalytic converter.
Some GM applications: P1357 indicates an ignition control output high or pulse detected when grounded on Cylinder 7. When the control module detects an unexpected signal, it sets these trouble codes.
Common Causes of the P1357 Code
Possible causes depend entirely on the specific vehicle application.
For Ford IDM applications, a failing crankshaft position sensor, damaged coil wiring, a poor electrical connection, or a failing powertrain control module can trigger the code.
For BMW misfire applications, a failing ignition coil, bad spark plug, failing fuel injector, or low engine compression on Cylinder 8 can cause the misfire.
For GM ignition circuit applications, an open or shorted ignition coil circuit on Cylinder 7, damaged wiring, or a failing coil can cause the fault.
Symptoms Associated With P1357
The primary symptom is an illuminated Check Engine Light.
On Ford applications, drivers may experience engine misfires, rough idling, hesitation, or a lack of power due to the ignition system malfunction.
On BMW applications, symptoms include a severe misfire on Cylinder 8, rough running, hesitation during acceleration, and potentially limp mode activation to protect the catalytic converter.
Diagnosing the P1357 Trouble Code
Diagnosis must begin by confirming the exact factory definition for the specific make, model, and year.
For Ford applications, technicians inspect the ignition coil wiring for opens or shorts, test the crankshaft position sensor, and verify the IDM signal using an oscilloscope or advanced scan tool.
For BMW applications, technicians swap the ignition coil and spark plug from Cylinder 8 to a known good cylinder to see if the misfire follows the component, then test the fuel injector and compression.
Repairing the P1357 Issue
Repairs follow the confirmed diagnosis for the specific application.
If an ignition coil or spark plug fails testing on a BMW or Ford application, replacing the confirmed failed component resolves the misfire or circuit fault.
If wiring damage or a poor connection is found in the IDM or ignition control circuit, repairing the harness restores the signal.
Cost Considerations for P1357 Repairs
Repair costs vary depending on the underlying fault and the vehicle application.
Replacing a spark plug or ignition coil involves standard parts and minimal labor. Diagnosing and repairing a damaged wiring harness or addressing internal engine mechanical issues requires more labor.
Cost depends on diagnostic time, component accessibility, required parts, programming requirements, and labor.
Prevention Strategies for Future Occurrences
Some electrical and mechanical failures cannot be reliably prevented.
Performing regular spark plug replacements at the manufacturer-recommended intervals helps prevent misfires caused by worn electrodes on applicable vehicles.
Inspecting exposed ignition wiring and keeping coil connectors clean can help prevent moisture intrusion and corrosion that lead to circuit faults.
Troubleshooting Tips and Best Practices
Never assume a manufacturer-specific code has a universal meaning. Always verify the exact factory service information for your specific vehicle.
Do not replace all ignition coils at once without verifying which cylinder is misfiring or which circuit is faulty.
If P1357 is accompanied by other random misfire codes, suspect a shared wiring harness issue, a failing powertrain control module, or a systemic fuel delivery problem.
More OBD-II Codes
| P1344 | P1345 | P1346 | P1347 |
| P1348 | P1349 | P1358 | P1359 |
| P1360 | P1361 | P1362 | P1363 |
| P1350 | P1351 | P1352 | P1353 |
| P1354 | P1355 | P1356 | P0300 |
| P0171 | P0174 | P0420 | P0430 |
Frequently Asked Questions
Is P1357 a generic OBD-II code?
No. P1357 is a manufacturer-specific code, meaning its exact definition and diagnostic procedure depend entirely on the vehicle’s make, model, and application.
Can I drive my vehicle with a P1357 code?
It depends on the application. If it indicates a severe misfire with fuel cut-off, driving the vehicle can cause catalytic converter damage and should be avoided until repaired.
Will a P1357 code cause my engine to misfire?
Yes. On applications where P1357 indicates an ignition coil circuit or specific cylinder misfire, the lack of spark or fuel will cause the engine to misfire and run rough.
Does P1357 always mean the ignition coil is broken?
No. The code often points to damaged wiring, a poor electrical connection, a bad spark plug, or a failing fuel injector rather than a mechanically failed ignition coil.
How do I clear a manufacturer-specific P1357 code?
Clearing the code requires fixing the underlying ignition circuit or misfire fault. Simply using a scan tool to erase the code will not repair the root cause.
What Should You Do About the P1357 Code?
Confirm the exact factory definition for your specific vehicle, then follow the applicable manufacturer diagnostic procedure for the relevant system and components.
Because P1357 is manufacturer-specific, testing the exact ignition coils, IDM circuits, or misfiring cylinders identified by the factory service information is required to find the root cause.
Once the fault is confirmed, perform the necessary repairs and verify the fix by clearing the codes and completing a test drive.
