Its a Hyundai trajet,AA said crankshaft sensor not working,can not find any mention of it in work shop manual

Those sensors are usually located somewhere near the actual crankshaft pulley. You might need to remove the covers over the timing belt to get to it. The photo below is only a guide for general appearance and position.

check masterswitch at driversdoor to see if switch has power or faulty relay.

Go to this URL: http://www.hyundai-forums.com/138-trajet-forum/89493-trajet-error-code-u0d00.html

It appears that another Hyundai owner had the same problem and sorted it out himself. U0D00 seems to be the Mass Airflow meter (sensor). Replace it and see how it performs. Good luck.

Is under crankshaft pulley.

could be a bad crank sensor, a bad crank sensor will let car run for a while then shut down and will not start for 10 to 15 min. and it will repeat this cycle if not fixed.the crankshaft position sensor provides the ignition module and pcm with a crankshaft position signal. the module uses this signal to determine spark for each cylinder. the pcm uses this signal for proper timing of engine.

it will probably be crank position sensor
this is located on the front of the engine where the engine meets the gearbox

take to autozone let them check for codes no charge for this

camshaft position sensor and one crankshaft position sensor

Go to http://www.hmaservice.com/ and register (vehicle by VIN). Afterward, you'll have access to technical information (manuals, wiring diagrams, service bulletins, etc) about your vehicle.