P04F4

Catalyst Heater Circuit Low Bank 1

Moderate severity

The control or supply line to the electric catalyst heater on bank 1 is shorted to ground or measures below the expected voltage when the heater is commanded on.

Common causes

Control line shorted to ground
One of the most commonly reported causes for this code — check this first.
high
Typical part cost: $330-2420
Heater element internally shorted
A plausible cause — test and verify before replacing parts.
medium
Typical part cost: $330-2420
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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

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Frequently asked questions

What does P04F4 mean?

P04F4 means "Catalyst Heater Circuit Low Bank 1". It is a generic OBD-II code that points to a fault in the auxiliary emission controls.

What are the most common causes of P04F4?

control line shorted to ground; heater element internally shorted; connector pins corroded - high contact resistance — 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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