If you do not clear out the DPF regularly, the backpressure can increase to a point that will effectively choke the engine exhaust and cause the engine or aftertreatment device to fail. To reach this point of filter loading, the operator has received and ignored several warning lights during several hours of operation. A red warning light means you need to pull over and call for your car to be recovered to a garage, you may also get an additional engine management light. Continuing to drive with a completely blocked DPF can cause engine damage. How to clear a blocked DPF. You can avoid all sorts of headaches if you deal with a DPF warning light as soon as tytWFOP.