P04F9

Catalyst Heater Circuit Intermittent Bank 2

Severity

⚠️ Medium

Can you drive?

Limited driving only, diagnose soon

Approx. repair cost

$56–278 (est.)

Symptoms

Check Engine light comes on
Decrease in catalyst efficiency
Possible errors in oxygen sensors
Increased fuel consumption

Causes

Open or short circuit in the heater circuit
Faulty heating circuit relay or fuse
Corrosion of connector contacts
Defective catalyst heating element
Problems with the control module

How to Fix

Visual inspection of the wiring harness and connectors
Checking the fuses and relays of the heating circuit
Diagnostics of heating element resistance
Checking control signals from the computer
Replacement of damaged components or the entire catalyst (if necessary)

Related codes

P0420 P0430 P0421 P0431