Question 1

What is the NOx sensor and what does it do?

Accepted Answer

The NOx sensor measures nitrogen oxides in diesel engine exhaust gases with SCR system (selective catalytic reduction). The information is sent to the ECU to control AdBlue injection and keep emissions within Euro 6 limits. It is mandatory in modern diesel vehicles.

Question 2

How do I know if my NOx sensor is faulty?

Accepted Answer

Failure signs: check engine light on, SCR system fault message on dashboard, excessive AdBlue consumption, power loss (limp mode) and MOT failure due to high emissions. The diagnostic unit will show codes P2201, P2202 or similar.

Question 3

How long does a NOx sensor last?

Accepted Answer

A NOx sensor can last between 100,000 and 160,000 km under normal conditions. Its lifespan is reduced with low-quality AdBlue, accumulated soot in exhaust, exhaust system leaks and prolonged use on short trips without complete DPF regeneration.

Question 4

Can a NOx sensor be cleaned or must it be replaced?

Accepted Answer

It cannot be cleaned effectively. NOx sensors have a precision ceramic element that deteriorates with use. Attempting to clean it can permanently damage it. If faulty, it must be replaced. Our sensors are OEM-equivalent with a 2-year warranty.

Question 5

Can I drive with a faulty NOx sensor?

Accepted Answer

Technically the car starts and runs, but it will enter limp mode reducing power. Additionally, driving with a faulty emissions control system is illegal, you won't pass MOT and fines can be high. Replace the sensor as soon as possible to avoid penalties.