Easy one-page printout for the garage or repair shop
This summary uses the existing diagnostic information shown in full below.
This code means that a part of the car that heats up a special fluid to clean the exhaust is using too much electricity.
The vehicle's computer has detected that the current (electricity flow) to the reductant heater C is higher than expected.
The reductant heater is part of the Selective Catalytic Reduction (SCR) system, which uses Diesel Exhaust Fluid (DEF) to reduce emissions. Heater C is responsible for ensuring the DEF remains at the correct temperature. If the current is too high, it may indicate a short circuit or a fault in the heater.
• Check Engine Light is on
• Possible decrease in fuel efficiency
• Emission test failure
• Short circuit in the heater wiring
• Faulty reductant heater C
• Defective control module
Reductant: A substance used to reduce emissions in the SCR system, typically Diesel Exhaust Fluid (DEF).
SCR: Selective Catalytic Reduction, a system that reduces nitrogen oxide emissions in diesel engines.
• Use an OBD-II scanner to confirm the code
• Inspect the wiring and connectors of the reductant heater
• Test the heater's resistance and current draw
• Repair or replace damaged wiring
• Replace the reductant heater C
• Replace the control module if necessary
• OBD-II scanner
• Multimeter
• Basic hand tools
$150 - $500
Moderate
• Ford F-250
• Chevrolet Silverado
• Ram 2500
• Regular maintenance of the SCR system
• Avoid using contaminated DEF
• Inspect wiring regularly
Sensor Issue
• Have the vehicle inspected by a professional
• Do not ignore the Check Engine Light
• Ensure DEF is topped up and of good quality
Check with the manufacturer for warranty coverage on emissions components.
This code has become more common with the increased use of SCR systems in diesel vehicles to meet emission standards.
Moderate – Addressing this issue is important to maintain emissions compliance and prevent further damage.
Ignoring emissions-related codes can lead to failing emissions tests and potential fines.
• Engine running
• DEF system active
The reductant heater is located near the DEF tank or lines, typically under the vehicle.
Q: Can I drive with a P221F code?
A: While the vehicle may still be drivable, it's important to fix the issue to maintain emissions compliance and avoid further damage.
Q: What happens if I ignore this code?
A: Ignoring this code can lead to increased emissions, potential fines, and damage to the SCR system.
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