1999 Vauxhall Astra engine management light on

Try taking off the throttle body, there is a cross drilling (very small one) clean it out and refit.

Vauxhall fault code p1515,

This car is fly-by-wire and there's a position sensor (potentiometer) fitted to the accelerator pedal - might be worth checking the wiring/connector for problems.

Also from VX forum ,

trouble code p1515
howdy,i've had my car diagnosed and the trouble code is p1515-this is something called a pedal tensionmeter fault.i've been quoted around the £340 mark to replace it but my friend who works in a vauxhall dealership says that there is some way to earth this sensor to stop it showing and somehow solve the problem.

thanks will try

thanks will try