I had an error code on my Plus8....downstream O2 sensor heater fault. Basically saying the sensor was not being preheated properly. The heater is there to get the sensor up to temperature quickly to get proper readings ( similar to a choke when cold starting a car). This sensor is there to check the cat is working properly. The upstream sensor is the really important one as it manages the engine. Mine were ok and the engine ran well. Using gomog I found the sensor ID from the Gems manual in there. Ordered two sensors from Rimmer Bros. After struggling to remove the faulty one I replaced it. Problem solved. The pre-heater fail fault sorted. No other faults so I assume the cat was ok. I still have one spare tucked away somewhere. These extensions look like a cheeky cheat that appears to work. I wonder if an eagle-eyed MOT tech would pick it up?
It prevents the ecu finding a fault so no MIL or code and a failed MOT. What about the " up the tailpipe" sensor during the test? Surely that would pick up a failed cat? The extenders cheat the ecu by reducing gas flow past the on-board sensor but the gases would still exit pass the test sensor?
