P2059: Reductant Injection Air Pump Control Circuit/Open
The P2059 code indicates a fault in the control circuit of the reductant injection air pump, which is part of the Selective Catalytic Reduction (SCR) system. This pump supplies air to assist in injecting diesel exhaust fluid (DEF) into the exhaust stream. An open circuit means there is a break in the electrical path, preventing the pump from operating. This can lead to incomplete DEF injection, causing increased NOx emissions and potential damage to the SCR system.
1. Most Common Causes
- Blown fuse for the reductant injection air pump circuit
- Open or shorted wiring in the pump control circuit
- Faulty reductant injection air pump relay
- Defective reductant injection air pump motor
- Corroded or loose electrical connectors
2. Symptoms You Will Notice
- Check Engine Light illuminated
- Reduced engine performance or power
- Increased exhaust emissions
- Possible regeneration issues in diesel particulate filter (DPF)
- Engine may enter limp mode
3. Step-by-Step Diagnosis
Step 1: Use an OBD2 scanner to confirm the P2059 code and check for related codes.
Step 2: Visually inspect the reductant injection air pump and its wiring for damage, corrosion, or loose connections.
Step 3: Check the fuse and relay for the pump circuit; replace if blown or faulty.
Step 4: Test the pump motor by applying direct battery voltage to see if it operates.
Step 5: Use a multimeter to check for continuity and voltage at the pump connector and control module.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended to drive long distances with this code, as it can lead to increased emissions and potential damage to the SCR system. The vehicle may enter limp mode, reducing power.
How much does it cost to fix?▼
The cost to fix P2059 typically ranges from $50 to $150 for parts like a fuse or relay, but if the pump needs replacement, it can be $200-$500 including labor.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.