Ford knox sensor
Have other folks had issues w/ Fords Knox sensors? If so, did your dealer tell you why it failed or triggered a engine light? Mine is telling me it's being tripped by using aftermarket fuel additives ...
Forum Discussion
ACZL, if it is a NOx sensor that your are referring to then yes aftermarket fuel additives could be the culprit. NOx is created when in cylinder temps get above 2,800F which a diesel engine normally does. To combat this, two things may happen. One, the EGR valve will open introducing cooled exhaust gas back into the intake to cool the in cylinder temps down. Two, if the SCR catalyst is hot enough, the system will inject more DEF if the NOx sensors detect more NOx downstream from the DPF.
You have NOx sensors at various parts in the exhaust/emissions system, and a fuel additive may alter NOx level. So basically what is happening is the ECM is triggering the EGR and SCR to combat the NOx being created, but the fuel additive may be making the engine run more efficient creating more NOx(yeah, an oxymoron). This will trigger a CEL because the engine is doing what it is programmed to in order to reduce NOx, but the amount is still not coming down to normal levels due to the fuel additive.
NOx and emissions devices is the real reason why diesel makes don't recommend additives anymore even though they want the best fuel possible ran through their engine and they do make them run more efficiently. If they recommend a fuel additive that increased NOx output or damages emissions equipment, then they could be liable.
You have NOx sensors at various parts in the exhaust/emissions system, and a fuel additive may alter NOx level. So basically what is happening is the ECM is triggering the EGR and SCR to combat the NOx being created, but the fuel additive may be making the engine run more efficient creating more NOx(yeah, an oxymoron). This will trigger a CEL because the engine is doing what it is programmed to in order to reduce NOx, but the amount is still not coming down to normal levels due to the fuel additive.
NOx and emissions devices is the real reason why diesel makes don't recommend additives anymore even though they want the best fuel possible ran through their engine and they do make them run more efficiently. If they recommend a fuel additive that increased NOx output or damages emissions equipment, then they could be liable.
