tom i have the same problem. from what i,m told the immobiliser is built into the engine ecu and the key has a chip . the chip is read by a skim at the ignition and compares it to code stored in the ecu.
but, every time the engine is started the codes change.
if the chip in the key loses the code (it happens magnets,mobile phones etc) the ecu will lock out after start up , you only get four start attempts and the ecu locks down (ie no engine crank)
have you a spare key?
there is an common problem it relates to the heater module and pin no. 21
check honest john fourm.
justin, November 2011
