How to Identify NOx Sensor Failure Symptoms

Like any other emissions component, a NOx sensor can fail over time. When that happens, the vehicle usually shows several warning signs that can help with diagnosis.

Engine warning lights come on

While the NOx sensor isn’t mounted on the engine bay, its failure can result in the engine light coming on. But, of course, the engine warning light can come on due to plenty of reasons, so don’t rush to conclude that it’s coming on due to the NOx sensor problems.

If you have an error code reader, use it to check the stored fault codes. If not, ask an experienced technician to carry out the diagnosis.

Your car can have plenty of error codes, and different codes have different meanings. For example, if you have a BMW car, some of the error codes that you might have include:

• 2AF2: 2B06; 2B09 nitric oxide sensor, Lambda linear
• 2AF4: 2B07; 2B0A NOx sensor, electrical
• 2AF6: 2AFB; 2B0B nitric oxide sensor, Lambda binary
• 2AF9:  NOx sensor, NOx signal: coast mode check
• 2EAE:  NOx sensor message missing (timeout)
• 30D6:  nitric oxide sensor, plausibility
• 30D8:  NOx sensor, Sensor damaged
• 30DA:  NOx sensor, heating time
• 30DC: nitric oxide senor, heating
• And many others

Increased fuel consumption

Have you noticed that your car has suddenly started consuming a lot of fuel? It could be due to a faulty NOx sensor. 

Without the sensor sending information to the engine, the engine management system can’t tell how the engine works in terms of fuel mixture and air-to-fuel ratio.

And due to this, the engine’s electronic brain assumes that your car is in the worst condition and enriches the fuel mixture to provide maximum power to the car.

It’s hard to be sure that the problem is due to a faulty NOx sensor, so before you jump to a conclusion, take your car to an experienced professional and have it inspected.