my 98 Nissan Altima engine light flashing off and on and knocking

country10

I have a 98 Nissan Altima I just got done 3days ago replacing the valve Pan cover gasket spark plugs and spark plug wires and even change the oil and oil filter before i went back over the road . Now she tells me shortly after I left she noticed the check engine light cap coming off and on now the motors knocking. Does anyone now what can be the problem ? It never done any of this till after I changed everything

ray80

Flashing CE light could indicate serious problem (not good to continue to drive it). It may be any number of things that may or may not be related to work you did. It will have to be scanned for trouble codes and addressed from there.

PF_Flyer

ray80 is right. Definitely shouldn't drive with a flashing CEL. I had a flashing CEL last year due to rodents chewing on my wiring harness. Rodents chewing on wires doesn't seem like it would be that serious, but the resulting shorts caused a timing problem and the car was spewing all kinds of smoke and started to run very rough. The fix was simple enough and took care of all the issues, but the engine needed to be checked for any damage that might have occurred in the short time it ran before I had it towed to the dealer. I got lucky and had no damage, but you need to find out what the cause is before you run it again.

Mr_Shiftright

yes, STOP driving the car with a flashing CEL. Sounds to me (just a guess) that you have a bad misfire, and this can destroy your catalytic converter--a big bucks item.