P1403 AUDI, VOLKSWAGEN: EGR SYSTEM CONTROL DIFFERENCE
P1403 BUICK, CADILLAC, CHEVROLET, GMC: EXHAUST GAS RECIRCULATION SYSTEM VALVE 1
POST UPDATED IN June, 2023
P1403 Code failures by brands
Description of DTC code P1403
The EGR (Exhaust Gas Recirculation) system is part of the vehicle’s emission control. Basically, it reduces the amount of NOx (Oxides of Nitrogen) produced by engine combustion significantly. This process is made by reducing the combustion temperature and diverting a small portion of the exhaust gases into the intake manifold.
The EGR flow is controlled by the PCM (Powertrain Control Module). On some vehicles, the EGR valve is controlled by a vacuum. On the most modern vehicles, it is operated by a built-in electric motor. The engine can open or close the valve gradually, as commanded by the PCM.
The position inlet valve of the Exhaust Gas Recirculation system is monitored by the PCM to ensure it responds to commands sent by the PCM. When the ignition switch is activated, the PCM memorizes the learned minimum EGR position. That minimum position is compared to that of the EGR Position Sensor when commanded to close the valve.
The P1403 OBDII diagnostic code, being a manufacturer-specific code, applies differently to each manufacturer. In most cases, it is used to signal a malfunction in the EGR system or the EGR valve.
Symptoms of fault code P1403
- Check Engine Lamp illuminated.
- The engine experiences loss of engine power.
- Increased fuel consumption.
- Engine has higher temperatures.
- Instabilities during idling.
Causes of OBD2 P1403
Reasons to set the P1403 OBD2 fault code:
- EGR wires or connectors may have damage.
- Exhaust Gas Recirculation System valve may be stuck.
- The Exhaust Gas Recirculation valve could be faulty.
Possible solutions of the DTC code P1403
Steps to resolve the DTC P1403 OBDII code:
- Consult the TSBs as a first step.
- Verify that the EGR valve is not blocked or attacked, allowing the vacuum to drop. Clean it and check for proper operation.
- Check all the electrical components that are related to the Exhaust Gas Recirculation system valve, and verify that they are all in good condition. Also, it is necessary to perform voltage tests on it and check that the voltage is the same as the manufacturer's specifications. Repair if necessary.
