2014 Volkswagen Jetta TDI - P0401 EGR Flow Insufficient

Question

I've got a 2014 Jetta TDI with 110k miles. The check engine light is on for P0401 (EGR flow insufficient). The car feels sluggish and the 'Diesel' smell from the exhaust is much stronger than it used to be.

I tried cleaning the EGR valve itself, which was pretty carboned up, but the code came back after 20 miles. I’ve heard this can be related to the DPF being clogged as well since they work in tandem on this emissions system.

EmissionsEric · Answer

Check the EGR vacuum solenoid (N18 valve). If the diaphragm in the actuator on the cooler is torn, it won't pull the valve open. You can test this easily with a handheld vacuum pump. If it doesn't hold vacuum, that's your problem.

TurboTina · Answer

On the CJAA engines, a P0401 is almost always a cracked DPF. When the DPF cracks, soot passes through it and enters the EGR cooler, which then clogs the tiny passages in the cooler. Wipe the inside of your tailpipe with a white paper towel—if it's black with soot, your DPF is cracked and you need a new DPF and EGR cooler.

2014 Volkswagen Jetta TDI - P0401 EGR Flow Insufficient

Suggest a repair