What it means
The control circuit for the intake air O2 sensor heater on bank 1 is open. Sensor cannot reach operating temperature.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
A heater inside the Bank 1 intake-air oxygen sensor warms the sensing element so the control module can use it sooner after a cold start. This code sets when the heater control circuit is open, so the heater cannot operate as commanded; the break may be in its wiring, heater element, or connector terminal.
Common causes
Most likely first.
- Open in heater control wire
- Open heater element
- Pin pushed back out of connector body
Symptoms
- Check engine light on after several drive cycles
- Slightly increased fuel consumption during cold start
- Delayed entry into closed-loop fuel control
- Failed emissions inspection (lambda readiness)
How to diagnose it
- Check freeze-frame data and readiness status to confirm that the fault appeared during a cold-start heater check.
- With the engine off, inspect the Bank 1 sensor heater connector for a pushed-back pin, corrosion, or an incompletely seated plug.
- Trace the heater wiring for breaks, melted insulation, or strain near the Bank 1 sensor and its harness route.
- Use the wiring diagram to check heater-circuit continuity and supply or control paths against the manufacturer's procedure.
- If the harness and connector are intact, test the Bank 1 sensor heater element and replace the sensor only if it is open.
Common fixes
- Seat the Bank 1 sensor connector and restore a pushed-back terminal.
- Repair an open or damaged wire in the Bank 1 heater control circuit.
- Repair a failed heater supply or control connection identified during circuit testing.
- Replace the Bank 1 intake-air oxygen sensor if its heater element is open.
Can I keep driving?
You can usually drive if the engine runs normally, but allow for less efficient cold-start operation and delayed mixture control. The heater fault can keep the oxygen-sensor readiness monitor incomplete and cause an emissions inspection failure.
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.