Reductant Injection Air Pressure Too High
The P20E7 code indicates that the engine control module (ECM) has detected excessive air pressure in the reductant injection system, which is part of the Selective Catalytic Reduction (SCR) system used to reduce NOx emissions. This high pressure can be caused by a faulty reductant injection pump, a blocked or restricted reductant injector, or issues with the air pressure sensor or its circuit. The system uses compressed air to atomize the diesel exhaust fluid (DEF) before injection into the exhaust stream. When air pressure exceeds the specified range, the ECM sets this code to prevent potential damage to the injection components or improper DEF dosing.
01. Most Common Causes
- Faulty reductant injection pump
- Blocked or restricted reductant injector
- Malfunctioning air pressure sensor
- Wiring or connector issues in the air pressure sensor circuit
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Reduced engine performance or power loss
- Increased exhaust emissions
- Possible DEF system warning messages on dashboard
03. Step-by-Step Diagnosis
Step 1: Use an OBD2 scanner to confirm the code and check for related codes.
Step 2: Inspect the reductant injection pump and air pressure sensor for physical damage or loose connections.
Step 3: Test the air pressure sensor signal with a multimeter and compare to manufacturer specifications.
Step 4: Check for blockages in the reductant injector by removing and inspecting it.
Step 5: If necessary, replace the faulty component (pump, sensor, or injector) and clear the code.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended to drive for extended periods as it can lead to reduced performance, increased emissions, and potential damage to the SCR system. Immediate diagnosis and repair are advised.
How much does it cost to fix?▼
The cost typically ranges from $150 to $400, depending on the root cause and labor rates. Replacing the reductant injection pump or sensor can be on the higher end.