DTC P1401: EGR Valve Control Negative Deviation (EGR EVRV Fault)
- Check the ''On Board Diagnostic (OBD) System Check''.
Was the OBD System Check performed?
YES – Go to step 2.
NO – Go to OBD System Check. 
- Check the DTC.
Are there DTCs P0562 or P1112 being output?
YES – Go to relevant DTC chart.
NO – Go to step 3.
- Check for the following conditions:
- Damaging EGR valve or EVRV
- EVRV hose vacuum leaks
- Vacuum leaks in EGR valve flange and pipes
Is a problem found?
YES – Repair as necessary.
NO – Go to step 4.
- Start the engine and allow it to idle.
- Check the MAF with the scan tool.
- While idling, jab the accelerator pedal about halfway down and immediately let the engine return to idle.
Did the MAF value on the scan tool show an immediate large change?
YES – Go to step 7.
NO – Replace the MAF sensor.
- Turn the ignition switch OFF.
- Remove the EGR valve.
- Check for the following conditions:
- Damaged EGR valve or EVRV
- EVRV hose vacuum leaks
- Vacuum leaks in EGR valve flange and pipes
- Visually and physically inspect the pintle, valve passages and adapter for excessive deposits or any kind of a restriction.
If a problem is found, clean or replace EGR system components as necessary.
Is a problem found?
YES – Repair the EGR valve.
NO – Go to step 11.
- Disconnect the EVRV connector.
- Measure resistance between the EVRV 2P connector terminals No. 1 and No. 2.
Is there about 14.7 – 16.1 ohms (20°C (68°F)) (At room temperature)?
YES – Go to step 13.
NO – Replace the EVRV.
- Remove the EVRV.
- Connect the hand vacuum pump (with gauge) to the EVRV (A).
- Apply 34 kPa (257 mm Hg, 10 in. Hg) of vacuum with hand vacuum pump.
Were vacuum leaks found?
YES – Replace the EVRV.
NO – Go to step 16.
- Remove the EGR valve.