DTC P0403 [LF]: Notes

DTC P0403 (LF) DETECTION CONDITION AND POSSIBLE CAUSE

DTC P0403	EGR valve (stepping motor) circuit problem
DETECTION CONDITION	The PCM monitors the EGR valve control signal voltage and current. If the following conditions are met, the PCM determines that there is the EGR control circuit problem. The PCM turns the EGR valve off, but the voltage of the EGR valve control signal remains low. The PCM turns the EGR valve on, but the current of the EGR valve control signal remains high. Diagnostic support note This is a continuous monitor (CCM). The MIL illuminates if the PCM detects the above malfunction conditions in two consecutive drive cycles or in one drive cycle while the DTC for the same malfunction has been stored in the PCM. PENDING CODE is available if the PCM detects the above malfunction condition during the first drive cycle. FREEZE FRAME DATA (Mode 2/Mode 12) is available. The DTC is stored in the PCM memory.
POSSIBLE CAUSE	EGR valve connector or terminals malfunction Open circuit or short to ground in EGR valve power supply circuits Short to ground in wiring harness between main relay and EGR valve terminal C Short to ground in wiring harness between main relay and EGR valve terminal D EGR valve power supply circuits related fuse malfunction Open circuit in wiring harness between main relay and EGR valve terminal C Open circuit in wiring harness between main relay and EGR valve terminal D EGR valve malfunction Short to ground in wiring harness between EGR valve terminal E and PCM terminal 2K Short to ground in wiring harness between EGR valve terminal A and PCM terminal 2G Short to ground in wiring harness between EGR valve terminal B and PCM terminal 2L Short to ground in wiring harness between EGR valve terminal F and PCM terminal 2H PCM connector or terminals malfunction Short to power supply in wiring harness between EGR valve terminal E and PCM terminal 2K Short to power supply in wiring harness between EGR valve terminal A and PCM terminal 2G Short to power supply in wiring harness between EGR valve terminal B and PCM terminal 2L Short to power supply in wiring harness between EGR valve terminal F and PCM terminal 2H Open circuit in wiring harness between EGR valve terminal E and PCM terminal 2K Open circuit in wiring harness between EGR valve terminal A and PCM terminal 2G Open circuit in wiring harness between EGR valve terminal B and PCM terminal 2L Open circuit in wiring harness between EGR valve terminal F and PCM terminal 2H PCM malfunction
Courtesy of MAZDA MOTORS CORP.

DTC P0403

EGR valve (stepping motor) circuit problem

DETECTION CONDITION

The PCM monitors the EGR valve control signal voltage and current. If the following conditions are met, the PCM determines that there is the EGR control circuit problem.
- The PCM turns the EGR valve off, but the voltage of the EGR valve control signal remains low.
- The PCM turns the EGR valve on, but the current of the EGR valve control signal remains high.

Diagnostic support note

This is a continuous monitor (CCM).
The MIL illuminates if the PCM detects the above malfunction conditions in two consecutive drive cycles or in one drive cycle while the DTC for the same malfunction has been stored in the PCM.
PENDING CODE is available if the PCM detects the above malfunction condition during the first drive cycle.
FREEZE FRAME DATA (Mode 2/Mode 12) is available.
The DTC is stored in the PCM memory.

POSSIBLE CAUSE

EGR valve connector or terminals malfunction
Open circuit or short to ground in EGR valve power supply circuits
- Short to ground in wiring harness between main relay and EGR valve terminal C
- Short to ground in wiring harness between main relay and EGR valve terminal D
- EGR valve power supply circuits related fuse malfunction
- Open circuit in wiring harness between main relay and EGR valve terminal C
- Open circuit in wiring harness between main relay and EGR valve terminal D
EGR valve malfunction
Short to ground in wiring harness between EGR valve terminal E and PCM terminal 2K
Short to ground in wiring harness between EGR valve terminal A and PCM terminal 2G
Short to ground in wiring harness between EGR valve terminal B and PCM terminal 2L
Short to ground in wiring harness between EGR valve terminal F and PCM terminal 2H
PCM connector or terminals malfunction
Short to power supply in wiring harness between EGR valve terminal E and PCM terminal 2K
Short to power supply in wiring harness between EGR valve terminal A and PCM terminal 2G
Short to power supply in wiring harness between EGR valve terminal B and PCM terminal 2L
Short to power supply in wiring harness between EGR valve terminal F and PCM terminal 2H
Open circuit in wiring harness between EGR valve terminal E and PCM terminal 2K
Open circuit in wiring harness between EGR valve terminal A and PCM terminal 2G
Open circuit in wiring harness between EGR valve terminal B and PCM terminal 2L
Open circuit in wiring harness between EGR valve terminal F and PCM terminal 2H
PCM malfunction

Courtesy of MAZDA MOTORS CORP.