Cause
Failed catalyst heater element
An electric heater bringing the catalytic converter to working temperature quickly after a cold start, since most emissions are produced before it lights off. The car drives normally without it, which is exactly why the fault gets ignored — the consequence is emissions and a monitor that never completes.
Typically specialist work. Needs equipment or training most home workshops do not have.
Codes this can cause (8)
Codes where this is a likely explanation first, rather than merely a possible one.
- P0423 Heated Catalyst Efficiency Below Threshold — Bank 1 Likely for this code Moderate
- P0424 Heated Catalyst Temperature Below Threshold — Bank 1 Likely for this code Moderate
- P0433 Heated Catalyst Efficiency Below Threshold — Bank 2 Likely for this code Moderate
- P0434 Heated Catalyst Temperature Below Threshold — Bank 2 Likely for this code Moderate
- P2AB1 Catalyst Heater Control Module Performance Likely for this code Moderate
- P2AB2 Catalyst Heater Control Module Supply Voltage Likely for this code Moderate
- P0429 Catalyst Heater Control Circuit/Open Bank 1 Low
- P0439 Catalyst Heater Control Circuit/Open Bank 2 Low
Information, not instruction
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Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
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