P1403 is a manufacturer-specific OBD-II diagnostic trouble code. Because it is manufacturer-specific, its exact definition depends entirely on the vehicle application, often relating to the exhaust gas recirculation (EGR) system.
The exact application must be verified before diagnosis. The code indicates a detected condition in the relevant EGR circuit or hoses, but testing is required to identify the root cause.
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Key Takeaways
- P1403 is a manufacturer-specific code, meaning its exact definition varies by automaker and vehicle application.
- On many Ford applications, it indicates that the Differential Pressure Feedback EGR (DPFE) sensor hoses are reversed or swapped.
- On certain Volkswagen and Audi applications, it relates to an EGR flow deviation or control valve regulation error.
- Diagnosis requires verifying the exact factory definition and inspecting the relevant EGR hoses, sensors, or control valves.
P1403 Code Description and Implications
P1403 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: P1403 indicates that the hoses connected to the Differential Pressure Feedback EGR (DPFE) sensor are reversed or installed backward.
Certain Volkswagen and Audi applications: P1403 indicates an EGR flow deviation or an EGR control valve regulation error.
Some Hyundai and Kia applications: P1403 may relate to an EGR valve position sensor circuit fault or an EGR stepper motor issue.
When the control module detects this condition, it sets this fault code. Because this is a manufacturer-specific code, the exact definition and diagnostic steps vary by automaker.
Common Causes of the P1403 Code
Possible causes depend entirely on the specific vehicle application.
For Ford DPFE applications, the primary cause is the physical reversal of the two vacuum hoses connected to the sensor during a previous repair.
For VW/Audi EGR flow applications, causes include heavy carbon buildup restricting the EGR passages, a failing EGR valve, or a faulty EGR temperature sensor.
For Hyundai EGR position applications, causes include a failed EGR valve assembly, damaged wiring, or a corroded connector.
Symptoms Associated With P1403
Symptoms vary based on the affected system and the specific vehicle application.
Drivers may notice an illuminated check engine light, rough idling, engine hesitation, or decreased fuel efficiency.
If the EGR system is completely blocked or stuck open, the engine may experience knocking, pinging, or stalling under load.
In some cases, the vehicle will fail an emissions inspection due to elevated NOx levels from the recirculating exhaust gases failing to enter the combustion chambers properly.
Diagnosing the P1403 Trouble Code
Diagnosis must begin by confirming the exact factory definition for the specific make, model, and year.
For Ford applications, technicians simply inspect the DPFE sensor hoses to ensure the larger hose is on the correct port and the smaller hose is on the other.
For VW/Audi applications, diagnosis involves checking for carbon blockages in the EGR valve and intake manifold, then testing the EGR valve operation using a scan tool.
For Hyundai applications, technicians test the EGR position sensor signal and verify the stepper motor operation.
Repairing the P1403 Issue
Repairs follow the confirmed diagnosis for the specific application.
If the DPFE hoses are reversed on a Ford, swapping them to the correct ports and clearing the code resolves the issue.
If carbon buildup is restricting flow on a VW/Audi, cleaning the EGR valve and intake passages restores proper operation.
If the EGR valve or position sensor fails electrical or functional tests, replacing the confirmed failed component is required.
Cost Considerations for P1403 Repairs
Repair costs vary depending on the underlying fault and the vehicle application.
Correcting reversed hoses involves minimal labor and no parts.
Cleaning carbon buildup from the EGR system or replacing the EGR valve involves standard parts and labor.
Cost depends on diagnostic time, component accessibility, required parts, programming requirements, and labor.
Prevention Strategies for Future Occurrences
Labeling or photographing vacuum hoses before removal during DIY repairs helps prevent accidental reversal of DPFE or EGR hoses.
Using high-quality fuel and occasionally driving at highway speeds can help reduce excessive carbon buildup in the EGR passages on direct-injection engines.
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 the EGR valve without first verifying the hoses, wiring, and actual flow through the passages. A simple hose swap or cleaning may resolve the issue.
If P1403 is accompanied by misfire or fuel trim codes, the diagnosis must address the combined system faults, as an EGR leak can cause a vacuum leak.
More OBD-II Codes
| P1394 | P1395 | P1396 | P1397 |
| P1398 | P1399 | P1432 | P1444 |
| P1445 | P1446 | P1447 | P1448 |
| P0440 | P0441 | P0442 | P0446 |
| P0455 | P0456 | P0171 | P0174 |
| P0300 | P0420 | P0430 | P0135 |
Frequently Asked Questions
Is P1403 a generic OBD-II code?
No. P1403 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 P1403 code?
It depends on the application. If the EGR is stuck open, you may experience rough idling or stalling. If it is a hose reversal, drivability may remain mostly unaffected.
Will a P1403 code cause an emissions failure?
Yes. The EGR system reduces NOx emissions. If the system is malfunctioning or blocked, the vehicle will likely fail an emissions inspection until repaired.
Does P1403 always mean the EGR valve is broken?
No. On Ford applications, it often simply means the DPFE sensor vacuum hoses were installed backward. On other makes, it may indicate carbon blockages rather than a failed valve.
How do I clear a manufacturer-specific P1403 code?
Clearing the code requires fixing the underlying hose, mechanical, or electrical fault. Simply using a scan tool to erase the code will not repair the root cause.
What Should You Do About the P1403 Code?
Confirm the exact factory definition for your specific vehicle, then follow the applicable manufacturer diagnostic procedure for the relevant system and components.
Because P1403 is manufacturer-specific, testing the exact hoses, sensors, or EGR valves 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.
