Check Engine

What is a NOx sensor error code?

Firstly, let’s examine the NOx sensor error code. NOx sensor development started in the 1990s and has become a particularly important part of the diesel engine. They are designed to measure both the oxygen level and the nitrogen level in the exhaust. The combination of these two chemical names resulted in the label ‘NOx’. The code pops up when there is an issue with the levels of chemicals, or when there is a problem with the sensor itself. It is really important to take a look at the underlying issues which might be causing this error. So today we are going to look at four iterations of this code: P11CC, P11DC, P11DB and P20EE. These error codes are commonly used in GM Vauxhall Opel Chevrolet GMC and many other car manufacturers.

Chevrolet Cruze

Fixing the NOx error code

There are some important similarities in the best way to approach these codes, but we are going to approach them separately here:

P11CC: The P11CC error code might be caused by a number of things. It could simply be an issue with the sensor itself, which would be best fixed by replacing the sensor, or the probe sensor. This might be especially true if there is a poor electrical connection. P11CC might also be caused by intake or exhaust system leaks. Before setting about fixing this problem, though, it important to rule out an issue with the sensor itself. You can rule this out by replacing the NOx sensor. If the replaced sensor still issues the same code, it may be time to investigate possible leaks.

P11DC & P11DB: The P11DC error code is similar, except that it is a fault specifically caused by the Nitrogen Oxide sensor. Again, the P11DB error code has similar causes: an issue with the electric circuiting of the NOx sensor, or a potential leak. Again it is wise to ensure the sensor is fixed before investigating possible leaks.

P20EE: The P20EE error code is a potentially more complex issue, with several possible causes. This code might indicate fuel contamination, or a problem with the diesel exhaust fluid, as well as being a prime indicator or exhaust leaks. However, it is once again caused also by a faulty NOx sensor, so it is still wise to replace the NOx sensor before investigating other causes. And you’ve guessed it, if the new sensor still produces the P20EE error code, then it might be time to get a mechanic to investigate more complex causes of the error.

Ofcourse none of the car dealers will be so helpfull and tell you how to fix it, they just say replace whole NOx control unit and you will spend so much money for parts which you don't need at first place, but ofcourse they wouldn't missout opportunity to loose profit by selling car parts, so this is like a"secret" which we are sharing with you and as always we try to save money for our customers and blog readers how fix their cars in the cheapest way.

Ofcourse in certain cases NS11A probe won't fix trouble codes, but just for an errors when it says there is no communication between nox sensor and car, all other error codes related to Nitrogen Oxide sensor will be fixed without a doubt.

Once replaced probe delete all trouble codes and go for a ride or replace and drive car evene you see CEL (Check Engine Light) on, it will dissapear after 30-40 miles or so.

These Diagnostic Trouble Code in short DTC are very common between Vauxhall Opel Astra Zafira Tourer Corsa Insignia Estate Sports Toure A MK1 B MK2 Mokka Mokka X SUV GM Chevrolet brand cars.

NOx fault codes and explanations

  • P11DC - NOx Sensor Current Performance Bank 1 Sensor 2
  • P11CC - Nox Sensor 1 Performance Signal Low
  • P11DB - NOx Sensor Current Performance Bank 1 Sensor 1
  • P11DB-00
  • P20EE - Nitrogen Oxide (Nox) Catalyst Efficiency below Threshold
  • P20EE00 - SCR NOx catalytic converter bank 1 error message: efficiency too. low sporadic fault
  • P2BAD - Exhaust Nitrogen Oxide (NOx) Concentration high
  • P11DC-00 NOx sensor 2 current Performance
  • P20BD
  • P220A - Nitrogen Oxide (NOx) sensor supply voltage circuit bank 1 sensor 1 current.
  • P1478
  • P11D8 Nox sensor 2 defective
  • P11D9 Nox sensor 2 low voltage
  • P22A4 Nox sensor 2 heating voltage too low
  • P22A8 NOx Sensor Heater Sense Circuit Low (Bank 1 Sensor 2)
  • P220B NOx sensor supply voltage - circuit malfunction (Bank 1 Sensor 2)
  • P220A  P220C
  • U029E Lost Communication with NOx sensor B

GM and Continental part numbers, which you could find at our store to replace faulty NOx control unit or if you decide to do DIY work and save a good amount of money you can buy our NS11A NOx sensor probe repair kit.

GM Opel Vauxhall part numbers:

Continental part numbers:

  • 55598161
  • 55500320
  • 55487270
  • 55570097 55500321 55495342
  • 55495029 SNS492 A2C16032700-01
  • 55598169 LW8169S 5WK97228
  • 55485493 LW5493S 5WK97263
  • 55485442 LW5442S 5WK97247

Cars using these part numbers:

  • Opel Vauxhall Astra J MK6 VI 1.6 CDTI 2.0 CDTi
  • Opel Vauxhall Astra MK7 VII  K
  • Opel Vauxhall Insignia & Sports Tourer 2.0 CDTi diesel
  • Opel Vauhall Zafira MK3 C Tourer P12 1.6 2.0 CDTi
  • Opel Vauxhall Insignia B MK2 2017 2018 2019 2020
  • Opel Vauxhall Insignia B MK2 Sports Tourer
  • Opel Vauxhall Insignia B MK2 Grand Sport Z18 2.0 CDTi
  • Opel Vauxhall Antara Cascada
  • Opel Vauxhall Mokka X
  • Chevrolet cars
  • 5WK9 7227
  • 5WK97227
  • A2C12686700-01
  • SNS168B
  • SNS168
  • 5WK96768
  • A2C90859700-02
  • LW0097S
  • 5WK9 6709A
  • 5WK96709A

More part numbers:

  • SNS427 A2C12454100-01 55487663
  • 55487659 0281006925/926

So why is it important?

The initial motivation for developing the NOx sensor was to create more eco-friendly cars, particularly for those with diesel engines. NOx gasses are a huge problem worldwide, with the noxious gasses emitted by car exhausts causing disruptive weather such as smog and acid rain. NOx sensors are a way to detect and then take steps to minimize poisonous exhaust fumes. As such it is really important to ensure your NOx sensor is fully working. Not least to comply with the most recent environmental regulations in your country.