DEF Supply Pump Pressure Low

What this code means

The DEF supply pump is not generating sufficient pressure to properly atomize DEF through the dosing valve.

Symptoms

• DEF system malfunction light
• Insufficient DEF dosing
• SCR efficiency reduced
• Potential derate
• Check Engine Light
• Poor atomization of DEF spray

Common causes

• DEF pump wear
• DEF filter clogged
• Air in DEF supply lines
• DEF line leak
• DEF frozen in lines or tank

Diagnostic steps

1. Check DEF supply pressure with scan tool
2. Inspect DEF filter condition
3. Check DEF lines for air leaks
4. Verify DEF line heaters working
5. Test pump motor operation

Repair notes

Replace DEF supply pump or filter. Purge air from DEF lines. Check and repair DEF line heaters for cold weather operation.

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