When the emissions are checked for the MoT test, on vehicles with lpg conversions is it checked when running on petrol or gas? I thought it was tested on what the vehicle was running on at the time it is presented for the MoT but my B-in-Law was told it has to be tested on petrol (and failed).
i had one in one in last week & how ever the vehicle is presented they have to test it, in your b inlaws case it was presented in lpg so it has to be tested as presented.
i should imagine they are not sure on how to test a lpg vehicle, id take it back & point them to the testers manual.
Vehicles which run on more than fuel (eg petrol and LPG) should be tested on the fuel they are running on when presented. There is a slight difficulty with LPG vehicles: the hydrocarbons are propane rather than hexane. So the HC reading obtained must be divided by the propane/hexane equivalency factor (PEF) marked on the gas analyser. For example: An LPG vehicle gives a HC reading of 700 ppm. The PEF marked on the machine is 0.48. So the actual MOT value is
700/0.48 = 1458 ie fail.
The vehicle has to be tested "as presented" - they can fail you on headlights if you have the electric headlight aim set incorrectly, even if a simple turn of the switch would make it pass.
Try fitting a cat replacement (i.e. empty) pipe on a LPG car and presenting it for the MOT on LPG - it will pass, even though the law says you must have a cat. The emmissions will be well below the allowed maximium.
Bob
I shall tell him to go back and have the thing rechecked running on lpg. From what I've googled it's the emissions that are checked not the cat, so as long as it passes the emissions it doesn't matter whether or not a cat is fitted.
What law says this?
I wonder if a hybrid that can be locked in 'battery' mode would work for this.
This may have changed. On my last MOT, the new computerised system was used. The system said LPG (as this is what's on my log book), & the tester said it had to be tested on this, & the limits were the same as for petrol, not the non-cat limits it used to be. My old car with it's closed loop system wouldn't have stood a chance, but this sequential system flew through.
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