e133 is a gas fault.
it could be no gas, low gas pressure, incorrect CO2 ratios, faulty gas valve, faulty ignition electrode, faulty spark generator, faulty flame sensing electrode or faulty pcb.
most likely it's the spark electrode, which may have bent due to explosive ignition if the CO2 ratios are incorrect, it's quite common and a service should sort it out.
Ian, September 2011
