What it means
The heater control circuit for the Bank 2 Sensor 2 heated oxygen sensor has a general electrical fault. This code does not identify whether the fault is an open, short, or another circuit problem.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
Bank 2 Sensor 2 is the heated oxygen sensor downstream of the catalytic converter on Bank 2. The control module monitors its heater control circuit and sets P0056 when it detects an electrical fault without specifying whether the circuit is open, shorted, or otherwise abnormal.
Common causes
Most likely first.
- Heater element open
- Wiring or connector fault
Symptoms
- Check-engine light on
- Oxygen-sensor heater may warm slowly
- Fuel economy may decrease
- Emissions may increase
How to diagnose it
- Capture freeze-frame data and scan for other heater-circuit codes that could indicate a shared fuse, relay, or supply problem.
- Locate Bank 2 Sensor 2 after the catalytic converter and inspect its connector and exhaust-side wiring for damage, corrosion, or a loose fit.
- Use the vehicle wiring diagram to identify the heater terminals, then check the circuit and heater element for open circuits or unintended shorts.
- Check that the heater has its specified supply and that the module-controlled side behaves as described in the manufacturer's diagnostic procedure.
- If the circuit and connector are sound, test the sensor heater against the manufacturer's specification before condemning the sensor.
Common fixes
- Reconnect or clean a poor Bank 2 Sensor 2 heater connector connection.
- Repair damaged or chafed wiring in the Bank 2 Sensor 2 heater circuit.
- Replace Bank 2 Sensor 2 if its heater element is open or out of specification.
- Repair a confirmed fault in the heater supply or control circuit.
Can I keep driving?
You can generally drive if the engine runs normally, but the downstream sensor may take longer to heat and emissions may increase. Avoid delaying diagnosis if an emissions inspection is due.
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.