NoX Sensor Repair, Removal, Deletion & Replacement Services
We remove, repair, delete and replace NoX sensors. Call us today for your NoX emission solution needs.
Below is a diagram of a generic Selective Catalytic Reduction (SCR) system used on many light-duty diesel trucks. The assembly uses two NOx sensors: the first sensor (NOx 1) is located near the turbo downpipe and measures engine out NOx. The second sensor (NOx 2) measures NOx levels exiting the SCR catalyst.
The SCR assembly contains a catalyst brick that requires DEF, or diesel exhaust fluid, for activation. A PCM controlled pump and valve are used to meter DEF into the exhaust system upstream of the SCR brick. With the exhaust heat, the DEF will decompose into ammonia and carbon dioxide.
If too much DEF is injected into the exhaust, the SCR brick can become saturated with ammonia and some of it will exit the SCR assembly. This is called “ammonia slip”. To a NOx sensor, ammonia and NOx look the same. Ammonia slip will cause the downstream NOx sensor to report an incorrect amount of NOx in the exhaust stream.
While addressing SCR codes concerning DEF quality, NOx sensor failure, or SCR efficiency, it may be necessary to “burn out” saturated SCR bricks and run the onboard diagnostic again. This can be accomplished by performing a manual DPF regen. The heat produced during the manual regen will remove ammonia from the SCR bricks and allow for a more accurate onboard SCR system diagnostic. Eurotune have NoX sensor solutions starting from just $395+GST. Call us today.