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 system, which checks the quality of a special fluid that helps reduce pollution, isn't working right.
The P21CE code is triggered when the vehicle's engine control module (ECM) detects a problem with the performance of the reductant quality module, which is responsible for monitoring the quality of the diesel exhaust fluid (DEF).
The reductant quality module is part of the diesel exhaust aftertreatment system. It ensures that the diesel exhaust fluid (DEF) used in selective catalytic reduction (SCR) systems meets the required quality standards. If the module detects that the DEF quality is out of specification or if the module itself is malfunctioning, it will trigger the P21CE code.
• Check Engine Light is on
• Reduced engine performance
• Increased emissions
• Contaminated diesel exhaust fluid (DEF)
• Faulty reductant quality module
• Electrical issues such as damaged wiring or poor connections
DEF: Diesel Exhaust Fluid, a solution used to reduce emissions in diesel engines.
SCR: Selective Catalytic Reduction, a method to reduce nitrogen oxides in diesel exhaust.
• Use an OBD-II scanner to confirm the P21CE code.
• Inspect the diesel exhaust fluid for contamination.
• Check the wiring and connections to the reductant quality module.
• Replace contaminated diesel exhaust fluid.
• Repair or replace damaged wiring or connectors.
• Replace the reductant quality module if faulty.
• OBD-II scanner
• Multimeter
• Basic hand tools
$200 - $600
Moderate
• Ford F-250
• Chevrolet Silverado 2500
• Ram 2500
• Regularly check and replace diesel exhaust fluid.
• Use only high-quality DEF.
• Perform routine maintenance checks on the exhaust system.
Sensor Issue
• Do not ignore the Check Engine Light.
• Have the vehicle inspected by a professional if you experience reduced performance.
• Regularly maintain the DEF system to prevent future issues.
Check with the vehicle manufacturer for warranty coverage on emissions-related components.
The P21CE code has become more common with the widespread use of SCR systems in diesel vehicles to meet stricter emissions standards.
Moderate – Addressing this issue promptly can prevent further emissions system damage.
Driving with a malfunctioning emissions system can lead to increased emissions and potential legal penalties.
• Vehicle must be running.
• DEF system must be operational.
The reductant quality module is typically located near the DEF tank or within the exhaust system.
Q: Can I drive with a P21CE code?
A: It's not recommended to drive for extended periods with this code as it can lead to increased emissions and potential engine performance issues.
Q: How often should I replace the diesel exhaust fluid?
A: Replace the DEF as recommended by the vehicle manufacturer, typically every 10,000 miles or as needed.
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