This Ford S Max had a high air flow code and exhaust bank 1 sensor code. We were called due to a garage not being able to fix this fault / the engine light returning after a short while of driving. We found when the vehicle was serviced the air duct around the MAF sensor wasn’t located correctly. As such this was causing un metered air flow to enter the engine and as such the engines ECU flagged this code. We advised a replacement MAF sensor would be a good idea due to it having a large amount of unfiltered air hitting the sensor. Due to how sensative these sensors are this would be the most logical route to take.
Once we relocated the air pipe correctly the MAF / air flow readings dropped straight away BUT they were slightly higher than usual ( hence our recommendation for sensor replacement ). Once the pipe was re-located the fault codes cleared and didn’t return. As a part of our service we also double checked the exhaust bank 1 sensor readings just to make sure all the correct readings and 12v & ground heater wires were present.
We also checked all live data readings on the EGR, Boost sensor, Bank 1 & 2 Exhaust sensors and DPF back pressure. We also found the DPF was around 70% filled and advised to do some longer drivers and rev the vehicles alot more. DPF filters on new diesels are a nightmare if you are doing alot of short drives.