P1373 is a manufacturer-specific OBD-II diagnostic trouble code. Because it is manufacturer-specific, its exact definition depends entirely on the vehicle application, ranging from ignition coil timing faults to valve lift control issues.
The exact application must be verified before diagnosis. The code indicates the control module detected a fault, but testing is required to identify the root cause and the specific affected component.
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Key Takeaways
- P1373 is a manufacturer-specific code, meaning its exact definition varies by automaker and vehicle application.
- On many Nissan, Ford, and GM applications, it indicates an early activation fault in the ignition coil for cylinder 3.
- On some Volkswagen applications, it points to an open ignition circuit on cylinder 7, while Porsche applications may flag a valve lift control fault.
- Diagnosis requires verifying the exact factory definition and testing the relevant ignition, sensor, or valve timing components.
P1373 Code Description and Implications
P1373 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 Nissan, Ford, and GM applications: P1373 indicates an Ignition Coil Cylinder 3 Early Activation Fault. The engine control module detects that the ignition coil for cylinder 3 is firing earlier than the expected timing parameters.
Some Volkswagen applications: P1373 indicates a Cylinder 7 Ignition Circuit Open. The control module detects an open circuit in the ignition coil control wiring for cylinder 7.
Some Porsche applications: P1373 indicates a Valve Lift Control fault, meaning the system detected a valve lift deviation above the specified limit value.
When the control module detects an unexpected signal, it sets these trouble codes.
Common Causes of the P1373 Code
Possible causes depend entirely on the specific vehicle application.
For Nissan, Ford, and GM ignition timing applications, a failing ignition coil, damaged coil wiring, a poor electrical connection, or a failing crankshaft position sensor can trigger the early activation fault.
For Volkswagen ignition circuit applications, an open or shorted ignition coil circuit on cylinder 7, damaged wiring, or a failing coil can cause the fault.
For Porsche valve lift applications, a failing valve lift actuator, low engine oil pressure, or a mechanical timing issue can cause the control deviation.
Symptoms Associated With P1373
The primary symptom is an illuminated Check Engine Light.
On ignition timing and circuit applications, drivers may experience engine misfires, rough idling, hesitation, or a lack of power due to the ignition system malfunction.
On Porsche valve lift applications, symptoms may include reduced engine performance, rough running, or the vehicle entering a fail-safe mode to protect the engine.
Diagnosing the P1373 Trouble Code
Diagnosis must begin by confirming the exact factory definition for the specific make, model, and year.
For ignition coil applications, technicians inspect the coil wiring for opens or shorts, test the coil primary and secondary resistance, and verify the crankshaft position sensor signals.
For Porsche valve lift applications, technicians inspect the engine oil level and pressure, test the valve lift actuator circuits, and check for mechanical binding in the valvetrain.
Repairing the P1373 Issue
Repairs follow the confirmed diagnosis for the specific application.
If an ignition coil or spark plug fails testing, replacing the confirmed failed component resolves the misfire or circuit fault. Repairing damaged wiring may also be necessary.
If a valve lift actuator fails electrical testing or is mechanically stuck on a Porsche application, replacing the confirmed failed actuator resolves the timing fault.
Cost Considerations for P1373 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 valve lift 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.
Performing regular oil changes using the manufacturer-recommended oil viscosity helps maintain proper oil pressure for variable valve lift systems and prevents sludge buildup.
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 P1373 is accompanied by other random misfire codes, suspect a shared wiring harness issue, a failing crankshaft position sensor, or a systemic fuel delivery problem.
More OBD-II Codes
| P1366 | P1367 | P1368 | P1370 |
| P1371 | P1372 | P1374 | P1375 |
| P1376 | P1377 | P1378 | P1380 |
| P0300 | P0301 | P0302 | P0303 |
| P0304 | P0305 | P0306 | P0335 |
| P0340 | P0011 | P0012 | P0016 |
Frequently Asked Questions
Is P1373 a generic OBD-II code?
No. P1373 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 P1373 code?
It depends on the application. If it indicates a severe misfire or valve timing issue, driving the vehicle can cause catalytic converter or engine damage and should be avoided.
Will a P1373 code cause my engine to misfire?
Yes. On applications where P1373 indicates an ignition coil circuit or early activation fault, the incorrect timing or lack of spark will cause the engine to misfire.
Does P1373 always mean the ignition coil is broken?
No. The code often points to damaged wiring, a poor electrical connection, a failing crankshaft position sensor, or a valve lift actuator issue rather than a failed coil.
How do I clear a manufacturer-specific P1373 code?
Clearing the code requires fixing the underlying ignition circuit, sensor, or valve timing fault. Simply using a scan tool to erase the code will not repair the root cause.
What Should You Do About the P1373 Code?
Confirm the exact factory definition for your specific vehicle, then follow the applicable manufacturer diagnostic procedure for the relevant system and components.
Because P1373 is manufacturer-specific, testing the exact ignition coils, crankshaft sensors, or valve lift actuators 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.
