Engine warning light (flashing heater coil) comes on after about 5 mins driving. OBD scanner came up with P242A (exhaust gas temp sensor) and P242B (exhaust gas temp sensor AND exhaust gas). I have replaced the EGTS and erased codes but still have the light coming on and reporting P242B. There's quite a lot of info on the P242A online, but I can't find anything on the P242B code. Any ideas?

Thanks

Update: A better quality OBD2 device reveals that it is the pre-DPF temp sensor that has failed (reading 999 deg C)

 

Further update: Whilst waiting for the new sensor to arrive I changed the air filter and fuel filter and put some DPF treatment in the tank. The sensor is now reading correctly and the problem has gone away.