P05EF

Symptoms

• AdBlue system fault warning
• Check Engine Light Is On
• Unstable operation of the SCR system
• Increased NOx emissions
• AdBlue pump is unstable or has reduced performance

Causes

• Oxidation of the pump power connector (increased resistance)
• Poor contact in the pump ground circuit
• Short circuit of the power supply to ground (additional voltage drop)
• Reduced on-board voltage (weak battery, faulty generator)
• Damage to the AdBlue pump wiring harness

How to Fix

1. Check the on-board voltage with the engine running (normal: 13.5–14.5V)
2. Check the voltage at the AdBlue pump power terminals when turned on.
3. Measure the voltage drop on the power circuit (no more than 0.5V is acceptable)
4. Clean and treat the contacts of the pump power connector
5. Check and clean the ground points of the AdBlue pump
6. Check the pump relay for voltage drop across the contacts

Related codes

Error P05EF by Vehicle Brand