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 the car's computer has detected a problem with the heater that keeps a special fluid in the car from freezing. It's like when your electric blanket doesn't work and you get cold.
The reductant tank heater is responsible for keeping the diesel exhaust fluid (DEF) from freezing in cold temperatures. Code P202B indicates that the control circuit for this heater is operating at a low voltage, suggesting a problem with the electrical circuit.
P202B is triggered when the powertrain control module (PCM) detects a low voltage condition in the reductant tank heater control circuit. This can be due to issues such as a faulty heater, poor electrical connections, or a malfunctioning PCM.
• Check engine light on
• Poor DEF system performance
• Possible freezing of DEF in cold weather
• Faulty reductant tank heater
• Poor electrical connections or wiring issues
• Malfunctioning powertrain control module (PCM)
PCM: Powertrain Control Module, the computer that controls engine and transmission functions.
DEF: Diesel Exhaust Fluid, a liquid used to reduce emissions in diesel engines.
• Use an OBD-II scanner to confirm the code.
• Inspect the wiring and connectors for the reductant tank heater.
• Test the reductant tank heater for proper operation.
• Repair or replace faulty wiring or connectors.
• Replace the reductant tank heater if faulty.
• Update or replace the PCM if necessary.
• OBD-II scanner
• Multimeter
• Basic hand tools
$200 - $600
Moderate
• Ford F-250
• Chevrolet Silverado
• Ram 2500
• Regularly inspect and maintain DEF system components.
• Ensure proper electrical connections.
• Keep the reductant tank heater clean and free from damage.
Sensor Issue
• Have the vehicle inspected by a professional if the check engine light is on.
• Avoid driving in extremely cold conditions until the issue is resolved.
Check with the vehicle manufacturer for warranty coverage on emissions-related components.
This code has become more common with the increased use of DEF systems in diesel vehicles to meet emissions standards.
Moderate – It should be addressed soon to prevent DEF freezing and potential emissions issues.
Driving with a malfunctioning DEF system can lead to increased emissions, which may not comply with legal standards.
• Cold weather conditions
• Vehicle at operating temperature
The reductant tank heater is located near the DEF tank, typically at the rear of the vehicle.
Q: Can I drive with a P202B code?
A: While the vehicle may still be drivable, it's best to address the issue to avoid DEF freezing and potential emissions problems.
Q: What happens if the DEF freezes?
A: If the DEF freezes, it can lead to reduced vehicle performance and increased emissions until it thaws.
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