986 2.7 2004 - Introduction - O2 codes + Fixing attempts

[naim22]

On 3/23/2020 at 12:34 PM, 986CKY said:

What engine management light is on the car? 

If a 4 sensor car is decatted then the rear two sensors that monitor cat efficiency will be switching like the pre cat sensors do for the closed loop fuelling. The DME will see this as an error as the rear sensors should be more or less constant voltage  (as the cat dampens and reduces the O2 levels by nature, by oxidising HC and CO to produce CO2 and H2O). This is how the catalytic converter efficiency is monitored.

However some RoW earlier vehicles (such as my 2000MY) did not come with a 4 sensor system, only 2 sensors before the cat to control the mixture, so I would expect no EML from decatting an earlier car

NAS market vehicles generally all come with 4 sensor systems due to differing emissions regulation at the time