What it means
The heated catalyst on bank 1 does not reach its target temperature within the expected time. Common causes are a defective heater element, supply fault, or a damaged temperature sensor.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
The Bank 1 heated catalyst has an electrical heater that helps it reach its target operating temperature. The control module monitors catalyst temperature and sets P0424 when the Bank 1 unit remains below the expected temperature threshold; a failed heater, its supply circuit, or the temperature sensor can cause the reading or heating to fall short.
Common causes
Most likely first.
- Heater element open or shorted
- Catalyst temperature sensor failed
Symptoms
- Check engine light on
- Failed emissions inspection
- Possibly slightly increased fuel consumption
- Sulfur (rotten egg) smell from exhaust under load
How to diagnose it
- Review freeze-frame data and scan for related heater-circuit, catalyst-temperature sensor, and efficiency codes to identify which part of the temperature system is implicated.
- Inspect the Bank 1 heater wiring, connectors, and temperature-sensor wiring for heat damage, corrosion, loose terminals, or exhaust leaks.
- Compare the reported Bank 1 catalyst temperature with ambient and engine warm-up data to spot a sensor reading that is implausible or stuck.
- Test heater power, ground, control, and the temperature-sensor circuit against the manufacturer's specification.
- If the circuits and sensor pass, assess the Bank 1 heater element and catalyst using the manufacturer's diagnostic procedure.
Common fixes
- Repair damaged wiring or loose connectors in the Bank 1 heater or temperature-sensor circuit.
- Replace a confirmed faulty Bank 1 catalyst temperature sensor.
- Repair a failed heater supply or control component identified by circuit testing.
- Replace the Bank 1 heated catalyst assembly if its heater element has failed.
Can I keep driving?
Gentle driving is generally possible if the engine runs normally, but the vehicle may fail an emissions inspection. Arrange diagnosis soon, and avoid heavy loads if there is a strong exhaust odor or loss of power.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.