2019 Volvo VNL 760 - SPN 5246 FMI 15 (SCR Inducement) and P20E8

Question

I am stuck at a rest stop with a '5 MPH Limited in 2 Hours' message on the dash. The main code is P20E8 which points to low DEF pressure. I can hear the pump trying to prime when I turn the key, but it just sounds like it's sucking air.

I filled the DEF tank to 100% just in case the gauge was lying. I checked the lines for kinks or leaks and didn't see anything obvious. I'm afraid to drive it because if that timer hits zero, I'm calling a tow truck. Is there a way to reset this or fix it on the shoulder?

ShopBossMike · Accepted Answer

✅ Confirmed fix: High probability it's the DEF tank header heater or a crystallized DEF line. However, the most common fix for P20E8 on the D13 is the DEF pump supply screen. There is a tiny screen inside the tank at the pickup. If you have compressed air, try blowing back through the supply line into the tank to clear the debris. It worked for me to get home, but eventually, I had to drop the tank and clean the 'DEF slime' out of the pickup tube.

SCR_Sergei · Answer

The DEF pump itself probably failed internally. They have a ceramic diaphragm that cracks. If you're hearing a 'clicking' rather than a steady hum, the motor is shot. You'll likely need the whole pump assembly unit.

2019 Volvo VNL 760 - SPN 5246 FMI 15 (SCR Inducement) and P20E8

Suggest a repair