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 exhaust is not working right because it's getting too much power.
The P20D4 code indicates that the control circuit for the Exhaust Aftertreatment Fuel Injector B is experiencing a high voltage condition.
The Exhaust Aftertreatment Fuel Injector B is part of the system that helps reduce emissions by injecting fuel into the exhaust stream. The control circuit for this injector is monitored by the engine control module (ECM). When the ECM detects a voltage that is higher than expected, it triggers the P20D4 code.
• Check Engine Light is on
• Possible reduction in fuel efficiency
• Potential increase in emissions
• Faulty Exhaust Aftertreatment Fuel Injector B
• Wiring issues such as short to voltage in the control circuit
• Faulty ECM
ECM: Engine Control Module
OBD-II: On-Board Diagnostics II
• Check for any other codes and address them first.
• Inspect the wiring and connectors for the injector for any signs of damage or corrosion.
• Test the voltage at the injector to ensure it is within specifications.
• Repair or replace any damaged wiring or connectors.
• Replace the Exhaust Aftertreatment Fuel Injector B if it is faulty.
• Reprogram or replace the ECM if necessary.
• OBD-II scanner
• Multimeter
• Basic hand tools
$200 - $600
Moderate
• Ford F-250
• Chevrolet Silverado
• Ram 2500
• Regular maintenance of the exhaust system
• Periodic inspection of wiring and connectors
• Use of high-quality fuel
Sensor Issue
• Do not ignore the Check Engine Light.
• Have the vehicle inspected by a professional if unsure.
• Consider regular diagnostics to prevent future issues.
Check with the vehicle manufacturer for specific warranty coverage on emissions-related components.
This code has been associated with vehicles that have advanced emissions systems to meet stringent regulations.
Moderate – Should be addressed to prevent potential damage to the emissions system.
Driving with a faulty emissions system may lead to failing emissions tests and is not environmentally friendly.
• Engine running
• Warm engine temperature
The Exhaust Aftertreatment Fuel Injector B is typically located near the exhaust system, often close to the catalytic converter.
Q: Can I drive with a P20D4 code?
A: While you may be able to drive, it's not recommended as it may lead to increased emissions and potential damage to the emissions system.
Q: How can I reset the Check Engine Light?
A: The light can be reset with an OBD-II scanner after the issue is fixed, but it may come back if the problem persists.
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Universal · Digital multimeter
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Helpful for checking voltage drops, grounds, and basic circuit health when modules are not communicating.
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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.