Reductant Supply Control Circuit Low
The P2063 code indicates that the powertrain control module (PCM) has detected a low voltage condition in the reductant supply control circuit, which is responsible for controlling the diesel exhaust fluid (DEF) pump or injector. This circuit is part of the selective catalytic reduction (SCR) system used to reduce NOx emissions. A low voltage reading suggests a short to ground, open circuit, or faulty component, potentially leading to inadequate DEF delivery and increased emissions.
01. Most Common Causes
- Faulty reductant supply pump
- Short to ground in the control circuit wiring
- Open circuit or poor connection in the harness
- Failed PCM (rare)
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Reduced engine performance or power
- Increased exhaust emissions
- Possible DEF system warning message on dashboard
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 supply pump and wiring for damage, corrosion, or loose connections.
Step 3: Test the control circuit voltage at the pump connector using a multimeter; compare to manufacturer specifications.
Step 4: Check for continuity and shorts to ground in the circuit between the PCM and the pump.
Step 5: If wiring is intact, test the pump resistance and operation; replace if faulty.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended to drive long distances, as the vehicle may enter limp mode and emissions will be elevated. Continued driving could damage the SCR system.
How much does it cost to fix?▼
The cost typically ranges from $50 to $150 for diagnosis and simple repairs like wiring fixes, but pump replacement can be more expensive.