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
- Signal wire shorted to ground
- Damaged sensor wires, terminals or connector
- The NOx sensor module: the sensor has its own small control unit on its lead, and it can fail too
What you can do yourself
- Check the sensor connector and power supply. NOx sensors often fail from heat and vibration.
- The NOx sensor is on the exhaust pipe, and its control unit is on the lead nearby, usually under the floor. Inspect the connector and lead for melting near the hot pipe, corrosion and water.
- If the fault isn’t fixed, after a while the engine will limit power or speed, and some cars won’t allow a restart. This is protection required by Euro 5 and Euro 6 rules: drive calmly to a service centre without delay.
Stop and don’t drive on if:
- The Check Engine light is flashing
- The temperature gauge is in the red or the overheating light is on
- The red oil pressure light is on
- Smoke from under the bonnet, a burning or petrol smell
- Strong jerking, knocking from the engine, or the car barely moves
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.
Find the part on Kaspi ShopBefore buying, check the part number or match the part by VIN in the Kaspi “Garage”.
The explanation comes from the error code reference in the AvtoElektrik PRO app.