Flashing CEL

[tms1989]

Hello! Yesterday I acquired a 2003 Silverado with 140,000 miles on the engine. Today I was going over the truck and I washed out the bottom very thoroughly. Got a little bit of rust dust and some chips of undercoating off. I really went to town cleaning the underside. After this I took the truck for a little drive and started to get a flashing check engine light. The truck seemed to drive fine at speed but when I pulled off onto a side street it felt like it was misfiring a little bit, rough idle. I turned off the truck and turned it back on and the flashing CEL returned after a few seconds. I started to head back home and after about 30 seconds the light went away. I have driven it a few times since then and nothing has come back. I had nothing before washing out the bottom.

 

What could be the cause of this?

 

Thanks for all replies!

[sefiroxx]

Need to pull codes for exact cause. Likely though, some moisture got in around soak plug wires or other sensor wire and caused solve short term short until it fried out.

[intheburbs]

Flashing CEL is a misfire.  It's possible something got too wet and was causing it, and once stuff dried out it went away.  I'd just keep an eye on it in case it returns.  Otherwise, just write it off as a learning experience not to douse things so much.