Reductant Pressure Too Low
The diesel exhaust fluid (DEF) system is not maintaining proper pressure.
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What it means (plain English)
The computer is seeing that the pressure of the diesel exhaust fluid (DEF) system is lower than it should be, which can lead to inefficiencies in emissions control.
What the computer is actually seeing
The engine control module (ECM) expects a minimum pressure of 30 psi (2.07 bar) in the DEF lines to ensure proper injection into the exhaust for reducing emissions.
What a healthy reading looks like
Actual DEF pressure should read 30-70 psi (2.07-4.83 bar) during normal operation, and the system should be able to maintain that pressure.
Guided diagnostic — the DiagCoach way
Don't just throw parts at it. Walk through these in order — each step tells you whether to keep going or stop and fix what you found.
- 1Check wiring and connectors for the DEF pressure sensor for damage or corrosion. Fix any issues found.
- 2Use a scan tool to check the DEF pressure sensor readings. If readings are below 30 psi (2.07 bar), replace the sensor if it is faulty.
- 3Inspect the DEF lines for blockages or damage. Repair or replace any found issues.
- 4Test the DEF pump operation. It should activate when the engine is running; ensure it operates at the correct pressure.
- 5Check DEF quality and level in the tank. Contaminated or low DEF can cause pressure issues.
Common causes
- Faulty DEF pressure sensor
- Blocked or damaged DEF lines
- DEF pump failure
- Defective DEF injector
- Leaking DEF tank or lines
Typical repair cost
$$$
Related codes
Frequently asked questions
Is it safe to drive with this code active?
It's best to fix this soon, as it may impact emissions and could lead to derate mode.
Will the code come back after clearing it?
If the underlying issue isn't fixed, the code will likely return.
Why is this code appearing with low DEF level?
Low DEF level can cause pressure reading issues, as the system won't have enough fluid to generate proper pressure.
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