Diagnostic trouble code P1356 is a manufacturer-specific powertrain fault code. Because it is manufacturer-specific, its exact definition depends entirely on the vehicle make, model, and application.
Exact vehicle application must be verified before diagnosis. The code identifies a detected condition in a specific subsystem, but further testing is required to identify the root cause.
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Key Takeaways
- P1356 is a manufacturer-specific code, meaning its definition varies between automakers like Ford and General Motors.
- On Ford applications, it indicates a loss of ignition diagnostic module input to the powertrain control module.
- On GM applications, it points to an ignition control output high or pulse detected when grounded on cylinder 6.
- Diagnosis requires verifying the exact factory definition and testing the relevant ignition circuits or modules.
- Repairs depend on the confirmed root cause and may involve replacing sensors, coils, or fixing wiring.
P1356 Code Description and Implications
Because P1356 is manufacturer-specific, there is no single universal definition. This error code identifies a detected condition, but the exact monitored system depends on the vehicle make and model.
Some Ford applications: P1356 indicates a “Loss of Ignition Diagnostic Module (IDM) Input to PCM” fault, meaning the module detects an open circuit or missing pulse from the ignition diagnostic monitor.
Certain General Motors applications: P1356 indicates an “Ignition Control (IC) Output High/Pulse Detected When Grounded” fault on cylinder 6, pointing to an electrical issue in the ignition control circuit for that specific cylinder.
Common Causes of the P1356 Code
The underlying cause depends entirely on the verified factory definition for the specific vehicle application.
For Ford applications, possible causes include a failing crankshaft position sensor, a faulty ignition control module, or damaged wiring in the IDM circuit.
For GM applications, causes may involve a failing ignition coil on cylinder 6, damaged ignition control wiring, or poor electrical connections at the coil harness.
Symptoms Associated With P1356
Symptoms vary widely depending on the underlying system fault and the vehicle manufacturer.
On Ford applications with an IDM input loss, symptoms can include a no-start condition, severe engine misfires, and an illuminated Check Engine Light.
On GM applications with a cylinder 6 ignition control fault, symptoms may include rough idling, hesitation during acceleration, and a noticeable misfire on that specific cylinder.
Diagnosing the P1356 Trouble Code
Diagnosis must begin by confirming the exact factory definition for the specific make, model, and year.
For Ford applications, technicians inspect the IDM circuit wiring for opens or shorts, test the crankshaft position sensor signals, and verify the ignition control module output.
For GM applications, technicians test the ignition control circuit for cylinder 6, inspect the ignition coil and wiring harness, and verify the powertrain control module signals.
Repairing the P1356 Issue
Repairs must follow confirmed diagnosis based on the specific vehicle application.
If an IDM circuit fault is confirmed on a Ford application, the damaged wiring must be repaired or the crankshaft position sensor or ignition control module replaced.
If an ignition control fault is confirmed on a GM application, the cylinder 6 ignition coil or damaged wiring must be replaced or repaired.
Cost Considerations for P1356 Repairs
Cost depends on diagnostic time, component accessibility, required parts, programming requirements, and labor.
Replacing an ignition coil or repairing a damaged wire may require minimal labor depending on accessibility.
Conversely, replacing an ignition control module or crankshaft position sensor on certain engines requires significant labor.
Prevention Strategies for Future Occurrences
Some electrical and mechanical failures cannot be reliably prevented.
Inspecting exposed wiring harnesses for chafing or heat damage can help prevent intermittent circuit faults in the ignition or sensor systems.
Keeping connector seals intact may reduce moisture intrusion that leads to corrosion and signal loss.
Troubleshooting Tips and Best Practices
Never assume P1356 is a universal ignition code. Always verify the exact definition for the specific vehicle before purchasing parts.
Do not ignore related codes. An IDM fault may appear alongside crankshaft position sensor codes, while an ignition control fault may appear alongside specific cylinder misfire codes.
Check for technical service bulletins applicable to your exact vehicle application, as manufacturers frequently release updated sensors or revised wiring harnesses for recurring faults.
More OBD-II Codes
| P1344 | P1357 | P0300 | P1108 |
| P1345 | P1358 | P0301 | P1109 |
| P1346 | P1359 | P0302 | P0171 |
| P1347 | P1360 | P0303 | P0174 |
| P1348 | P1361 | P0304 | P1580 |
| P1349 | P1362 | P0305 | P1542 |
Frequently Asked Questions
Is P1356 a generic or manufacturer-specific code?
No. P1356 is a manufacturer-specific code. Its exact definition varies significantly between automakers, so the factory service information for the specific vehicle must be consulted.
Can I drive my car with a P1356 code?
It depends on the application. If P1356 indicates a loss of ignition diagnostic input, the engine may stall or fail to start. If it is a cylinder 6 ignition fault, performance may be reduced.
Will disconnecting the battery clear the P1356 code?
Disconnecting the battery may temporarily clear the code, but it does not repair the underlying electrical or mechanical fault. The code will return once the monitor runs again.
Can a bad crankshaft position sensor cause a P1356 code?
On Ford applications monitoring the ignition diagnostic module, a failing crankshaft position sensor can prevent the module from generating the required IDM pulse, triggering the fault code.
Does P1356 always mean the ignition control module is bad?
No. While a failing module is a cause on specific applications, the code can also indicate damaged wiring, a failing ignition coil, or a faulty crankshaft position sensor.
What Should You Do About the P1356 Code?
Confirm the exact factory definition and diagnostic procedure for your specific vehicle application. Because P1356 is manufacturer-specific, identifying whether it relates to an ignition diagnostic module circuit or a specific cylinder ignition control fault is mandatory.
Follow the applicable manufacturer diagnostic steps to test the relevant system and components. Once the root cause is confirmed, complete the necessary repairs and verify that the system operates correctly and the code does not return.
