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 helps clean the air from the engine is getting too hot. It's like when you touch a hot stove and it's too hot to touch.
The code indicates that the Selective Catalytic Reduction (SCR) system, which reduces nitrogen oxides (NOx) emissions, is experiencing an over-temperature condition in Bank 2.
P20F1 is triggered when the Engine Control Module (ECM) detects that the temperature of the SCR NOx pre-catalyst in Bank 2 exceeds the manufacturer's specified limits. This could be due to excessive exhaust temperatures or a malfunctioning temperature sensor.
• Check Engine Light is on
• Decreased fuel efficiency
• Possible limp mode activation
• Faulty temperature sensor
• Excessive exhaust temperatures
• Malfunctioning SCR system
SCR: Selective Catalytic Reduction
NOx: Nitrogen Oxides
ECM: Engine Control Module
• Use an OBD-II scanner to confirm the code.
• Inspect the temperature sensor and wiring for damage.
• Check the exhaust system for blockages or damage.
• Replace the faulty temperature sensor.
• Repair or replace damaged wiring.
• Inspect and repair the exhaust system.
• OBD-II scanner
• Multimeter
• Temperature probe
$200 - $600
Moderate
• Ford F-250
• Chevrolet Silverado
• Ram 2500
• Regularly maintain the exhaust system.
• Ensure proper engine tuning.
• Use the correct type of fuel.
Sensor Issue
• Do not ignore the Check Engine Light.
• Have the vehicle inspected by a professional.
• Avoid driving under heavy load until repaired.
Check with your vehicle manufacturer for specific warranty coverage related to emissions systems.
This code has become more common with the increased use of SCR systems in diesel engines to meet emissions standards.
Moderate – Address the issue soon to prevent possible damage to the SCR system.
Driving with a malfunctioning emissions system may violate emissions regulations and could result in fines.
• Engine at operating temperature
• Vehicle in motion
The SCR NOx pre-catalyst is located in the exhaust system, typically near the engine in Bank 2.
Q: What happens if I ignore this code?
A: Ignoring this code can lead to increased emissions, reduced fuel efficiency, and potential damage to the SCR system.
Q: Can I drive with a P20F1 code?
A: While the vehicle may still be drivable, it's best to address the issue promptly to avoid further damage.
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Network faults often require full-system access instead of a generic code reader alone.
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Universal · Digital multimeter
A solid entry-level multimeter for voltage, continuity, resistance, and basic electrical troubleshooting.
Helpful for checking voltage drops, grounds, and basic circuit health when modules are not communicating.
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Universal · Wire connectors and repair kit
Useful when diagnosis points toward damaged wiring, corroded terminals, or connector repairs.
Useful if diagnosis points toward damaged connectors, wiring, or terminal repairs.
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Fitment Required · Vehicle-fitment part
Relevant when catalyst-efficiency or emissions faults persist after proper diagnosis.
Catalyst-efficiency faults sometimes point toward converter problems after proper testing.
Catalytic converters are highly vehicle-specific and should not be purchased by code alone.
View options on AmazonThese parts may be related to this fault category, but a code by itself does not confirm exact fitment or guarantee that replacing a part will solve the problem.