P05F7

Symptoms

• Immediate warning of AdBlue/SCR system failure
• Complete failure of the exhaust aftertreatment system
• Check Engine Light Is On
• Increased NOx and soot emissions
• Engine power limitation

Causes

• Mechanical jamming of relay contacts in the open position
• Break inside the relay (burnt contacts)
• Blown relay load circuit fuse
• ECU malfunction (no control signal)
• Break in the power wire at the relay output

How to Fix

1. Check the presence of a control signal on the relay from the ECU (multimeter or oscilloscope)
2. If there is a control signal, replace the relay
3. Check the relay load circuit fuse
4. Check the voltage at the input and output of the relay when trying to turn on
5. If there is no control signal from the ECU, diagnose the ECU
6. Replace the relay and check the system

Related codes

Error P05F7 by Vehicle Brand