Engine light lit and runs very rough

i had a drive thru car wash with an undercoating cleaner. immediately upon pulling away from the stall, my car ran very rough. after about 2-3 miles the engine light came on. i parked it immediately. is this the fault of the car wash, or a big coincidence?

It is probably due to the car wash, but not the fault of the car wash. Spark plug cables are the most likely culpret, but could be anything, if it has been hot and dry it may be fine now. Mileage and year?

year: 2000, mileage: 121,000

What’s the code? The CEL on means the computer is storing a DTC (Diagnostic Trouble Code).

As Busted suggested, get the codes read.

And as Waterboy suggested, the wash got something wet. Nut in the case of modern cars that could be any number of things. Water could have even gotten drawn into the air snorkle and damaged the Mass AirFlow sensor.

The codes will set you free. Post them here.