Low AdBlue level or blocked filter in the pump module; Failed AdBlue pump; Leaking or blocked supply line; Crystallised AdBlue in lines or connectors; Faulty pressure sensor.

SCR / AdBlue

P20E8 Reductant (AdBlue/DEF) Pressure Too Low

Q: What does P20E8 mean?

Reductant (AdBlue/DEF) Pressure Too Low. The ECU monitors the pressure in the AdBlue (DEF) supply system using a pressure sensor, usually in the pump module. P20E8 is set when the pump cannot build up or hold the target pressure.

The ECU monitors the pressure in the AdBlue (DEF) supply system using a pressure sensor, usually in the pump module. P20E8 is set when the pump cannot build up or hold the target pressure.

Common causes

Low AdBlue level or blocked filter in the pump module
Failed AdBlue pump
Leaking or blocked supply line
Crystallised AdBlue in lines or connectors
Faulty pressure sensor

Typical symptoms

AdBlue or emissions warning and check engine light on
AdBlue dosing disabled
Countdown to engine start restriction on many vehicles
Reduced power or limp mode

P20E8 and NuoVolta

If the SCR/AdBlue system has been removed or disabled for off-road or motorsport use, where permitted by law, the NuoVolta AdBlue / SCR / NOx Removal solution adjusts the ECU calibration and the DTC removal feature can disable this code. On a working system, check the AdBlue level, lines and pump first.

AdBlue / SCR / NOx Removal Available for 121 ECUs

Related codes

P203FReductant (AdBlue/DEF) Level Too Low P2047Reductant (AdBlue/DEF) Injector Circuit/Open (Bank 1 Unit 1) P20EESCR NOx Catalyst Efficiency Below Threshold (Bank 1)

Diagnose and repair real faults first. Removing or disabling emission systems is only permitted where allowed by law, for example for off-road or motorsport use.