Reductant Injection Air Pressure Too Low
The P20E6 code indicates that the engine control module (ECM) has detected the reductant (DEF) injection air pressure is below the required threshold. This system uses compressed air to atomize and inject diesel exhaust fluid (DEF) into the exhaust stream for selective catalytic reduction (SCR). Low air pressure can result from a faulty air pump, clogged air lines, leaks, or a defective pressure sensor, leading to insufficient DEF delivery and increased NOx emissions.
1. Most Common Causes
- Faulty reductant injection air pump
- Clogged or leaking air lines
- Defective air pressure sensor
- Blocked air filter or intake
2. Symptoms You Will Notice
- Check Engine Light illuminated
- Reduced engine performance or power
- Increased exhaust emissions
- Possible DEF system warning message
3. Step-by-Step Diagnosis
Step 1: Use a scan tool to confirm P20E6 and check for related codes.
Step 2: Inspect air lines for leaks, kinks, or blockages.
Step 3: Test the reductant injection air pump operation and pressure output.
Step 4: Verify the air pressure sensor reading with a multimeter or scan tool.
Step 5: Check the air filter and intake for restrictions.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended to drive long distances as it can cause increased emissions and potential damage to the SCR system. You may experience reduced power and fuel economy.
How much does it cost to fix?▼
Repair costs typically range from $150 to $600, depending on the root cause. Replacing the air pump can cost $200-$400, while sensor replacement or line repair may be less.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.