What are the common causes of P0429?

An open in the catalyst heater circuit on bank 1. A failed catalyst heater element. A blown heater fuse. Corrosion at the heater connector. An ECM driver fault on the heater control.

Check the heater fuse and relay first. Test the heater element resistance. Check the heater circuit for an open. Inspect the heater connector for corrosion. Replace the heater element or repair the open wire. Clear the code and retest.

P0429

Catalyst Heater Control Circuit/Open Bank 1

System: Auxiliary emission controls (P code)
Lamp: Check Engine Light
Category: Powertrain - Auxiliary Emissions Controls

What it means

P0429 means Catalyst Heater Control Circuit/Open Bank 1.

Check these first

An open in the catalyst heater circuit on bank 1
A failed catalyst heater element
A blown heater fuse
Corrosion at the heater connector
An ECM driver fault on the heater control

What to do next

Check the heater fuse and relay first
Test the heater element resistance
Check the heater circuit for an open
Inspect the heater connector for corrosion
Replace the heater element or repair the open wire
Clear the code and retest

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Updated

Generic SAE J2012 definition. Last updated 2026-10-10.