What's a CEL anyways? :confused:
 

Until now the newest car I'd owned was a 1979 VW. Now I've got this 1990 Metro and it has a learning curve. Clickbait title -- I know what a Check Engine Light is. I've done my due diligence, I gave Google two pages to find a result.

The situation. Turn the key on and the light flashes a 12. Which is supposed to be 'cleared for flight'. Don't know why I hadn't noticed it earlier.

But lately, on the road and under power there's nothing, but at a slack or trailing throttle it throws random ones, twos and threes.

Help me Eco-modder, you my only hope.

Crud, OBD1 & it's cryptic coded messages that don't help diagnosis. You need a paperclip to start self check.

Firstly, a good decrudding of the ground connections is in order, along with a long grok of the description of cause found somewhere online. It's 20+ years old and a lot of the control harness has become brittle and inflexable, subject to intermittent signal when the engine moves on decel...

If the light doesn't stay on, it technically isn't a CEL. It needs to be ON or flashing about once a second.

They are one second flashes. I'll be asking the mechanic I bought it from, but I can't reach him on the weekend.

Another oddity is that when the gas gauge registers Full, there's a bright dot to the left of Empty the back of the gauge.

At least it keeps life interesting. :)

Ones twos threes? Isn't it supposed to show some of these numbers:

https://www.troublecodes.net/gmimport/

That's the list I'd found. I get the 12 on ignition on, which is reassuring, but there are no single digit codes, which suggests some intermittent electrical fault.

Piotrsko -- Can you explain about the paper clip?

You can find a how-to and codes on GMF:

https://geometroforum.com/check-engi...guide-t10.html

The paperclip is rebent to assist shorting 2 female pins on the obd connector typically in the engine compartment thus forcing the computer to barf appropriate codes somewhere on the panel ostensibly to aid in fault diagnosis. Which pins? Model and maker specific.