I just had a head gasket repaired on 2006 Ford Taurus. Also replaced water pump, serpentine belt, and thermostat. Now that the head gasket is repaired- idle is rougher than before engine trouble, brakes are too tight and car won't start. Panel says check charging system also check engine light is on (but light has been on for about 1 year- I figured it was a sensor). I think it may be the timing chain (mechanic never said it needed to be replaced). Battery, starter and alternator replaced about 8 months ago. Mechanic said I might need an O2 sensor because of the water that was in the engine valve. He never mentioned the timing chain but after doing some research online I think that might be the problem. Any help is much appreciated.

 

I think you might need another mechanic.