Check Engine light -- valves just adjusted

Less than 100 miles ago, valves adjusted on 01 CRV. More "clicking" now than before, but at least I know they aren't tight. Tonight, my daughter announced that the check engine light came on and stayed on. Gas cap was tight. I also noticed what sounds like a small leak near header/exhaust pipe junction just behind the engine.

Would maladjusted valves (too loose?) cause the check engine light to come on?

Would a new exhaust system leak cause the check engine light to come on?

I don't have access to OBD II computer, and I prefer to avoid taking it back to place that adjusted valves if valve adjustment is the problem as I suspect they'd deny any responsibility.

Thanks.

I don't have access to OBD II computer....

AutoZone will pull codes for free.

Without the code, all you'll have is conjecture.

***new exhaust leak? Are you sure some crack-head wasn't trying to cut the convertor off?***

Take the vehicle to Auto Zone or another major place like that. They read codes for free.

It is tough to diagnose without the code...

Had it checked. Sometimes simple is easy. Bad gas cap -- wouldn't seal even though it "clicked" shut. Bad O ring, I guess. Bought new cap, check engine light stayed out. Odd coincidence.