I hope you car is indica or indigo.
they have potentiometer problem and check engine light come on.
Changing them will not only stop the check engine light , but also give /feed proper fuel to engine.
Potentiometer is present in fuel pump , in indica /indigo the blue colour thing you find in the pump.
and the work of potentiometer is explained by "tasuray" INFO
In crdi units , the accelerator is the potentiometer. That is there is no accl cable in modern cars