What it means
The NOx sensor on bank 1 sensor 3 reports a calibration memory check-sum failure - factory calibration data corrupted or unreadable.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
The Bank 1 Sensor 3 NOx sensor stores calibration data used to interpret its measurements. P23BC sets when the control module cannot verify that stored data, such as when the calibration memory check fails or the data cannot be read reliably.
Common causes
Most likely first.
- Calibration memory corrupted
- Module software outdated, reflash may resolve
- Supply voltage outside specification
Symptoms
- Check engine light
- Possible NOx or aftertreatment warning
- Increased NOx emissions or failed emissions test
How to diagnose it
- Use a scan tool to save freeze-frame data and check for supply-voltage, communication, or other NOx sensor faults that could affect calibration memory checks.
- Inspect the Bank 1 Sensor 3 connector and supply wiring for loose terminals, corrosion, or damage that could interrupt power.
- Check sensor supply and ground conditions against the manufacturer's specification, including for voltage instability associated with the fault.
- Check whether the vehicle manufacturer specifies a software update or calibration procedure for this code, and follow that procedure if applicable.
- If supply and wiring are sound and the fault returns after any specified software action, test or replace the Bank 1 Sensor 3 NOx sensor as directed by the manufacturer.
Common fixes
- Restore a poor sensor supply or ground connection.
- Repair damaged or corroded Bank 1 Sensor 3 wiring and connector terminals.
- Correct an identified supply-voltage problem affecting the sensor.
- Apply a manufacturer-specified software update or calibration if it addresses the memory check fault.
- Replace the Bank 1 Sensor 3 NOx sensor if its calibration memory remains unreadable after circuit checks.
Can I keep driving?
The vehicle may remain drivable, but unreliable NOx readings can affect aftertreatment monitoring, raise emissions, and cause an emissions test failure. Arrange diagnosis soon, particularly if an aftertreatment warning accompanies the check engine light.
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.