P0400

Exhaust gas recirculation (EGR) system malfunction

Detection Conditions

• Difference in intake manifold pressure when EGR is operated and when it is stopped is too small or too large

Diagnostic Support Notes

• This is an intermittent monitor (EGR)
• Check engine indicator illuminates if the ECU detects the above malfunction condition in two consecutive drive cycles
• PENDING CODE is available
• DIAGNOSTIC MONITORING TEST RESULTS available
• FREEZE FRAME DATA is available
• DTC is stored in ECU memory

Possible Causes

• EGR valve malfunction
• MAP sensor malfunction
• MAP sensor solenoid valve malfunction
• EGR gasket malfunction or damage
• EGR vacuum solenoid valve malfunction
• EGR vent solenoid valve malfunction
• ECU malfunction

[P0400 - From 2002 Mazda Millenia factory service manual]