Service Engine Soon/heater Blowing Cold Air?

[michaelf]

Service light came on and within 15 minutes my heater is blowing cold air. Could the problems be related? There are no other obvious issues, Any ideas? 1999 Silverado w/ 137,000 miles.

 

Thanks

[cmoore74]

Your thermostat may be failed and stuck open. Is your engine temperature low? That would cause both the engine light and lack of heat. You would also be getting terrible gas mileage.

[SoCalChris]

Could also be a vacuum leak. Open your hood, and listen for a hissing sound while the engine is running.

[michaelf]

engine temp is normal, i'll listen for the hissing sound. Thanks

 

Mike

[michaelf]

update...I checked for hissing, lite whisper maybe, so I wiggled a couple hoses, added a full can of sea foam and about a 1/2 tank of 92 octane gas.."service engine soon" went out about 30 miles later.....light has been off ever since. So, what was the light all about? Stuck o2 sensor? someting got cleaned out? loose vac tube? Every time I start her now I'm lookin' for the light! 137, 400 miles and running like a champ! But she still makes me nervous!

 

Mike