What it means
The drive circuit for the heated catalyst on bank 1 is open. Heated catalysts use an electrical heating element to reach light-off temperature within seconds of cold start.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
A heated catalyst on bank 1 uses an electrical element to warm the catalyst quickly after a cold start. The control module monitors the heater drive circuit and sets P0429 when it detects an open path, so the heater may not operate and the catalyst may take longer to reach effective temperature.
Common causes
Most likely first.
- Heater element or wiring open
- Pin pushed back out of connector body
- Cracked solder joint inside the module or sensor
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
- Check freeze-frame data and related codes to confirm the fault occurred during a cold-start heater command and note any supply or control-circuit codes.
- With the system cool and power off as directed by the manufacturer's service information, inspect the bank 1 heater connector for a backed-out pin, corrosion, or heat damage.
- Inspect the heater wiring for breaks, rubbed insulation, or damage near the exhaust and check that the connector is fully seated.
- Test the heater element and circuit continuity against the manufacturer's specification to locate the open.
- If the element and wiring pass, verify the heater drive output and module connections before considering an internal control-module fault.
Common fixes
- Seat the heater connector and correct a pushed-back terminal.
- Repair an open or damaged section of heater wiring.
- Replace the bank 1 catalyst heater element or assembly if it is open by specification.
- Repair the control-module connection or module only if testing confirms the drive circuit fault is internal.
Can I keep driving?
You can usually drive gently if the engine runs normally, but avoid repeated short cold trips because the catalyst may warm slowly and emissions can rise. Have it checked promptly if the check-engine light flashes, the engine runs poorly, or exhaust odor becomes strong.
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.