P05F8
Reductant Heater Control Module Performance
The reductant heater module is electrically intact but does not deliver the expected thermal effect - heater elements aged, supply line resistance, or thermostat sensor offset.
The reductant heater module is electrically intact but does not deliver the expected thermal effect - heater elements aged, supply line resistance, or thermostat sensor offset.
Common causes
- high
Heater element aged
One of the most commonly reported causes for this code — check this first.
Typical part cost: $130-660
- low
Module software outdated, reflash may resolve
Less common, but worth ruling out after the more likely causes.
Typical part cost: $130-660
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First things to check
- 1Confirm the code with a scan tool and check for additional related codes.
- 2Inspect the relevant sensors, wiring, and connectors for damage or corrosion.
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Related codes
See related trouble codes
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Frequently asked questions
What does P05F8 mean?
P05F8 means "Reductant Heater Control Module Performance". It is a generic OBD-II code that points to a fault in the vehicle speed, idle control, auxiliary inputs.
What are the most common causes of P05F8?
heater element aged; module software outdated, reflash may resolve; supply voltage outside specification — these are the most commonly reported causes. Verify with a proper diagnosis before replacing parts, or use the Wrenchify app for a vehicle-specific diagnosis.
Can I keep driving with this code?
The vehicle is usually drivable for short distances, but the problem can worsen or affect emissions. Diagnose and repair as soon as practical. Use the Wrenchify app for a full diagnosis specific to your vehicle.
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