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Flashing CEL no stored codes

Kevinreitan

By Kevinreitan
in Ask A GM Technician

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Kevinreitan Enthusiast

Kevinreitan

Posted
Posted

My 2003 1500 has been having an intermittent issue with a flashing CEL. it only happens when going hwy speed 45 mph+ up hill, as soon as i either slow down or the road flattens out the CEL stops flashing. my basic scan tool has not been able to pull any codes after this happens. Other that this the truck runs good, most of my commute driving is on flat ground. Just trying to find some ideas i can check out before i have to spend any money on it.

 

2003 silverado 1500

4.3L 83k miles

Swimmer8366 Enthusiast

Swimmer8366

Posted
Posted

Cat convert broken up than shifting to plug exhaust system? Sounds dumb...... fuel related?

 

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Jsdirt Senior Enthusiast

Jsdirt

Posted
Posted

Blinking light means there's a cat-melting misfire - SEVERE, in other words. I swear the 4.3 had misfires right off the showroom floor ... but I digress.

 

It sounds like the misfire gets worse under load. In that case, you COULD have an ignition problem (plugs, wires, cap/rotor, ignitor, wiring, etc..), or, there could be a fuel delivery problem resulting in a lean misfire (clogged fuel filter, failing fuel pump, failed regulator, etc..)

 

Without scan data, we're all just pissin' in the wind ...

Swimmer8366 Enthusiast

Swimmer8366

Posted
Posted

Start with fuel pressure than get back to us. And scan it for data and get back to us with exact cylinders.

 

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Swimmer8366 Enthusiast

Swimmer8366

Posted
Posted

I read a post a while back with binding valves on cylinder 5....

 

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