Hi. I replaced a broken vacuum line in my engine bay (short line from intake manifold to MAP sensor) last night. On my way home from work today, CEL went away. Yea! So, I figured I'd put my cheap little OBD scanner on and see what it said.

- p0120, p0400
-CEL off
- Indicators
- Inc (Comp, EGR)

Cleared codes, retested:

- No codes
- CEL off
- Indicators
- Inc (EGR)

It did this while ignition on, but engine off.
It did this while driving and rescanning.

What kind of problem would an EGR system have that shows up on an OBD scanner (Actron CP9125) but doesn't throw a code?

Thanks!

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