Easy one-page printout for the garage or repair shop
This summary uses the existing diagnostic information shown in full below.
This code means there's a problem with a part of the car that helps keep a special fluid warm. This fluid is used to clean the car's exhaust. If it's not warm enough, it can't do its job properly.
The P20C2 code indicates an issue with the performance of the control circuit for the third reductant heater in the vehicle's exhaust system.
The reductant heater is part of the Selective Catalytic Reduction (SCR) system, which uses a fluid called Diesel Exhaust Fluid (DEF) to reduce emissions. The heater ensures the DEF doesn't freeze in cold temperatures. Code P20C2 is triggered when the Engine Control Module (ECM) detects a performance issue in the control circuit for the heater labeled 'C'.
• Check Engine Light is on
• Reduced engine performance
• Increased emissions
• Faulty reductant heater
• Poor electrical connection in the heater circuit
• Blown fuse or relay for the heater circuit
Reductant: A substance used to reduce emissions in the exhaust system.
DEF: Diesel Exhaust Fluid, a liquid used in SCR systems to reduce emissions.
• Use an OBD-II scanner to confirm the code
• Inspect the wiring and connectors for the reductant heater
• Check the fuse and relay associated with the heater circuit
• Replace the faulty reductant heater
• Repair or replace damaged wiring/connectors
• Replace blown fuses or faulty relays
• OBD-II scanner
• Multimeter
• Basic hand tools
$200 - $500
Moderate
• Ford F-250
• Chevrolet Silverado 2500
• Ram 2500
• Regular maintenance of the SCR system
• Ensure DEF is topped up and of good quality
• Inspect wiring and connections periodically
Sensor Issue
• Do not ignore the check engine light
• Get the vehicle inspected by a professional
• Avoid using low-quality DEF
Check with the vehicle manufacturer as emissions-related components may be covered under warranty.
This code has become more common as emissions standards have tightened, requiring more complex exhaust treatment systems.
Moderate – While the vehicle may still run, emissions and performance could be affected.
Driving with this issue may result in higher emissions, which could lead to fines in areas with strict emissions testing.
• Vehicle must be at operating temperature
• Cold ambient conditions may be required to test heater function
The reductant heater is typically located near the DEF tank or within the SCR system lines.
Q: Can I drive with a P20C2 code?
A: While you can drive, it is not recommended as it may lead to increased emissions and reduced performance.
Q: How do I know if the reductant heater is faulty?
A: A diagnostic scan showing P20C2 and inspection of the heater and its circuit can confirm the fault.
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