In the shop - EXHAUST FLUID QUALITY POOR
EXHAUST FLUID QUALITY POOR message
June 12 36619 miles. Cleared after adding 2 ½ gallons of DEF and driving 5 highway miles. Codes read on my Edge Insight CTS:
P20EE SCR NOx Catalyst Efficiency Below Threshold Bank 1
P207F Reductant Quality Performance
P229F NOx Sensor Circuit Range/Performance (Bank 1 Sensor 2)
July 10 37320 miles. Cleared at 37343 miles – same afternoon – highway driving
P20EE SCR NOx Catalyst Efficiency Below Threshold Bank 1
P207F Reductant Quality Performance
Called the dealer and explained my issue and he recommend clearing the codes and bring it in again if it repeats. I discussed the filling of the tank and that there is no more room to add more to the tank. We discussed purchasing DEF and he told me to be cautious of purchasing when it is stored in direct sunlight. I explained where I purchased DEF and that was not the case.
He said if the message comes back bring the truck in and it will be fixed - no appointment required.
July 24 37834 Message came back
P20EE SCR NOx Catalyst Efficiency Below Threshold Bank 1
P207F Reductant Quality Performance
Truck is in the ship for repairs - most probable cause is NOX sensor #2 - they have been replacing a few of them. DEF quality has not normally been the problem.
If #2 sensor readings are "faulty" the ECM is programed to assume it is due to DEF quality.
When using two NOx sensors in a urea SCR system, the upstream sensor is used to estimate what amount of DEF needs to be injected ahead of the SCR catalyst to achieve optimal NOx conversion. The downstream (post-catalyst) sensor is then used to check the results. Under ideal conditions, NOx conversion will be high and very little ammonia slip will occur.
June 12 36619 miles. Cleared after adding 2 ½ gallons of DEF and driving 5 highway miles. Codes read on my Edge Insight CTS:
P20EE SCR NOx Catalyst Efficiency Below Threshold Bank 1
P207F Reductant Quality Performance
P229F NOx Sensor Circuit Range/Performance (Bank 1 Sensor 2)
July 10 37320 miles. Cleared at 37343 miles – same afternoon – highway driving
P20EE SCR NOx Catalyst Efficiency Below Threshold Bank 1
P207F Reductant Quality Performance
Called the dealer and explained my issue and he recommend clearing the codes and bring it in again if it repeats. I discussed the filling of the tank and that there is no more room to add more to the tank. We discussed purchasing DEF and he told me to be cautious of purchasing when it is stored in direct sunlight. I explained where I purchased DEF and that was not the case.
He said if the message comes back bring the truck in and it will be fixed - no appointment required.
July 24 37834 Message came back
P20EE SCR NOx Catalyst Efficiency Below Threshold Bank 1
P207F Reductant Quality Performance
Truck is in the ship for repairs - most probable cause is NOX sensor #2 - they have been replacing a few of them. DEF quality has not normally been the problem.
If #2 sensor readings are "faulty" the ECM is programed to assume it is due to DEF quality.
When using two NOx sensors in a urea SCR system, the upstream sensor is used to estimate what amount of DEF needs to be injected ahead of the SCR catalyst to achieve optimal NOx conversion. The downstream (post-catalyst) sensor is then used to check the results. Under ideal conditions, NOx conversion will be high and very little ammonia slip will occur.
