2.0 TDCI MAF fault - DTC Code P00BD (& frequent white smoke)

Hoping for a little steer in the right direction please, so can be efficient with trying to find the root of the issue with limited time on my hands.

The issue - Have had intermittent Engine malfunction lights for a couple of weeks now, but have had little time to look at it properly. EM light comes on, car goes into limp mode, still drives fine, just with less oomph than you'd like up the steep hills of Cumbria! When I say intermittent there is no pattern. Sometimes happens at low speed/throttle just minutes into the drive, sometimes not for 3 or 4 days, then next time is under load 30mins into a drive etc, no pattern related to temperature or driving style.

FORScan reading pulls up DTC code P00BD inidicating MAF reading issues. Full read pasted below.

Tried so far - Changed air filter just to be sure breathing properly. - Removed MAF sensor, looked good and clean, but cleaned anyway by way of a good spraying with contact cleaner. - Sprayed immediately obvious vacuum hoses around the area with brake cleaner to see if revs change, no response. Haven't had time to go deeper around the engine with the carb or brake cleaner method. 

Related or perhaps just coincidental issue - She's been producing white smoke a little more often than I would like. It seems like regen is happening quite frequently, and is triggered very easily. Within about 2 or 3 miles of leaving work in warm weather there is a big hill, and if she's up to temp I often pull out on the dual carriage way section to pass all the slow traffic uphill, and this often triggers a regen even within 150 miles of the last one. The bizarre thing is one cold mornings it can do the same within 1 to 2 miles of leaving the house, with the temp gauge only just having jumped from blue to grey, but still fairly low. White puffs produced on gentle acceleration, and the engine note/throttle response has changed as if in regen. Soot readings checked t'other day were down to 27% and the kpa at idle was 0, so all seems good in the DPF. - Since cleaning the wee sponge filter in the vacuum valve located just to the left of the airbox exit pipe (believe it may be a turbo pressure solenoid?) this white smoke issue has lessened significantly, but still happened once on a relatively cold engine. 

Any pointers appreciated please! Should I be looking deeper for air leaks in the system after the MAF sensor? If so are there any favourite spots to target? Should I just buy a MAF sensor and whack it on to see if solves the issue?

Cheers, Jamie

===PCM DTC P00BD:64-27===
Code: P00BD - Mass or Volume Air Flow 'A' Circuit Range/Performance - Air Flow Too High

Additional Fault Symptom (:64):
 - Signal Plausibility Failure

Status (-27):
 - DTC Present at Time of Request
 - Malfunction Indicator Lamp is Off for this DTC

Module: Powertrain Control Module

 Freeze Frame  #1:
-EVENT_TIME: 395046619 s (Tue Jul 01 08:43:09 2025) - Event time
-TOTAL_DISTANCE: 111006 miles - Total Distance
-MODULE_VOLTAGE: 14.3 V - Control Module Voltage
-ESTSECRK: No  - Engine status - engine in crank
-ESTSERUN: Yes  - Engine status - engine running
-INCAR_TEMPERATURE: 69 °F - In car temperature
-OUTDOOR_TEMPERATURE: 66 °F - Outside temperature
-PWR_MODE_QF: Power Mode Undefined  - Power Mode Quality Factor
-LOAD: 25.49 % - Calculated Load Value
-ECT: 174 °F - Engine coolant temperature
-MAP: 26.0 psi - Manifold absolute pressure sensor
-RPM: 1418 1/min - Engine Revolutions Per Minute
-VSS: 46.0 mph - Vehicle Speed
-IAT: 68 °F - Intake Air Temperature
-MAF: 0.65 lb/min - Mass Air Flow
-FRP: 14910.1 psi - Fuel Rail Pressure
-BARO: 14.5 psi - Barometric pressure
-APP_D: 22.35 % - Accelerator Pedal Position D
===END PCM DTC P00BD:64-27===