P2051 - Reductant Injection Valve Circuit Low Bank 2 Unit 1
The P2051 code indicates that the powertrain control module (PCM) has detected a low voltage condition in the reductant injection valve circuit for Bank 2, Unit 1. This valve is part of the Selective Catalytic Reduction (SCR) system, which injects diesel exhaust fluid (DEF) into the exhaust stream to reduce NOx emissions. A low circuit condition typically means the voltage is below the expected range, often due to a short to ground, open circuit, or faulty valve.
01. Most Common Causes
- Faulty reductant injection valve
- Short to ground in the valve circuit
- Open circuit in the wiring or connector
- Corroded or damaged connector pins
- Failed PCM (rare)
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Reduced engine performance
- Increased NOx emissions
- Possible limp mode activation
03. Step-by-Step Diagnosis
Step 1: Use a scan tool to retrieve all stored codes and freeze frame data.
Step 2: Visually inspect the reductant injection valve connector and wiring for damage, corrosion, or loose connections.
Step 3: Measure voltage at the valve connector with the ignition on; should be battery voltage (12V). If low, check for short to ground or open circuit.
Step 4: Test the valve resistance with a multimeter; compare to manufacturer specifications (typically 10-30 ohms).
Step 5: If wiring and valve are okay, suspect a PCM fault; perform a PCM test or reprogramming.
04. Commonly Affected Makes
05. 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 reduced engine performance, increased emissions, and potential damage to the SCR system. The vehicle may enter limp mode, limiting speed and drivability.
How much does it cost to fix?▼
The cost to fix P2051 typically ranges from $50 to $150 for diagnosis and repair, depending on the cause. Replacing the reductant injection valve can cost $100-$300, while wiring repairs are usually less expensive.