A fault code doesn’t yet mean the unit or sensor itself is faulty: often it’s the plug and connector leading to it.
Possible causes
- Exhaust leak before the sensor
- A leaking injector: fuel still flows with the throttle closed
- Sensor
- O2 sensor wiring or connector
What you can do yourself
- When you lift off the throttle the fuel is cut and the sensor should show a lean mixture. If it doesn’t, check the exhaust for leaks and look at the sensor on the “Sensors” tab.
OOleg’s tip: check the connector
Often the cause is simple — there is no contact in the connector (plug). Look at the connector from the back: remove the rubber seal and you will see whether a wire is corroded or has come off completely. Corrosion shows up as green deposits. Ideally, gently pull each wire towards you one at a time: a sound wire stays in place, while a corroded one simply comes off — it needs to be repaired.
Unplug and inspect connectors with the ignition off.
Bank 1 is the side of the engine with cylinder 1. An inline engine only has bank 1.
The explanation comes from the error code reference in the AvtoElektrik PRO app.