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2002 BMW 325xi Question: failed emissions
Answer #1ZeeTech November 11, 2010, 17:09Master
P0455 (Evaporative System Leak Detected - Large Leak)
Mostly it caused by incorrectly sealing gas cap. Make sure it's tight and seals good.
Of course there could be other leak also, for that you need a shop who can trace down EVAP system problems. It usually requires a smoke pump.
Your other code, the P0128 - Coolant Thermostat/Valve Temperature below control range. Get the electrical thermostat replaced. Make sure there is OE (blue color) antifreeze in the cooling system, if not, get it flashed out and refill it with the OE fluid. You are looking at more expensive problems if there is other fluid in it.