P0056 code meaning
HO2S Heater Control Circuit (Bank 2 Sensor 2)
Powertrain system Generic code P00xx codes Check engine light
What P0056 means
The heated oxygen sensor on bank 2 is the downstream sensor 2 behind the (first) catalytic converter, used mainly to monitor the converter. Its heating element brings it quickly to operating temperature. Typically the heater receives battery voltage via a fuse, and the engine control module switches the ground side with a pulsed signal while checking that the circuit state matches the command. P0056 is the general circuit fault: the measured state of the heater circuit does not fit the command, most often because the circuit is interrupted. Which physical fault sets the general, low or high code is defined by each manufacturer. Without heating, the sensor becomes ready late and catalyst monitoring may not complete. Bank 2 codes occur only on engines with two exhaust banks (V or boxer engines).
P0056 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modeNot expected
- Repair difficultyMedium, DIY possible
- Typical labor0.3 to 1.5 hours
- Clears after repairAfter a drive cycle
Symptoms of P0056
- Check engine light on
- Usually no noticeable drivability problem
- Catalyst monitor does not complete
- Emissions test or readiness check failed
Common causes of P0056
- Most likelyHeating element inside the sensor burnt out
- Most likelyWire or connector damaged by heat or road spray
- PossibleHeater fuse blown; a shared fuse can set several heater codes
- Less likelyOutput driver or software of the engine control module
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Oxygen sensor downstreamOxygen sensor heaterOxygen sensor wiringOxygen sensor heater fuse
What each part of P0056 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 0 | Area: fuel and air metering and auxiliary emission controls. |
| 56 | The exact fault in that area. |
What to do next
- Note P0056 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P0056
What does P0056 mean?
P0056 means "HO2S Heater Control Circuit (Bank 2 Sensor 2)". The heated oxygen sensor on bank 2 is the downstream sensor 2 behind the (first) catalytic converter, used mainly to monitor the converter. It is a generic code, so it means the same on every make.
Is it safe to drive with P0056?
Usually yes, for a short time, if the check engine light is steady and the car drives normally. If the light flashes or the car runs badly, stop and have it checked.
Will P0056 fail an emissions test?
Yes, it can. P0056 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P0056 to fix?
Difficulty: medium. A typical repair takes 0.3 to 1.5 hours of work. A careful DIY repair is possible with basic tools and a scanner.
Will P0056 clear itself after the repair?
After the repair the car has to complete a drive cycle (a mix of city and highway driving) before the test runs again. Until then the readiness monitor shows "not ready", which can fail an inspection.