A slew of codes and a stumped mechanic

[Emilio]

So I recently had my check engine light come on and it was accompanied by a bunch of codes which are as follows;

ECM-120D - air mass signal too low
ECM-121B - MAF sensor flow too low
ECM-212C - long term fuel trim, bank 1 signal too high
ECM-216D - long term fuel trim, bank 1 signal too low
ECM-21E0 - long term fuel trim, bank 1 faulty signal
ECM-614B - exhaust camshaft control - faulty
ECM-671C - camshaft position, exhaust - high

The car recently had the head rebuilt after burning a valve. At that time the plugs, fuel filter, timing belt and air filter were changed.

My mechanic has cleaned the cam solenoid and associated filter and checked for vac leaks with no luck and is a bit stumped. I don't know what codes are being thrown since that has been done.

What are we missing?

[Antherzoll]

How long after the head rebuild did the codes show up?

[Emilio]

How long after the head rebuild did the codes show up?

A couple months.

[Willy]

Some guesswork: :)
If the MAF sensor's signal is faulty, couldn't then the first 2 codes be the result?
And if the air mass measurement is faulty, possibly fuel trim will become abnormal as well,
perhaps explaining the next 3 codes and possibly also the last 2 codes since the cam
positions are also air mass dependent.
So maybe all the codes are the result of a single fault, a malfunctioning MAF sensor.
Willy

[hoonk]

The cams were out and retimed and the entire intake system was taken apart and reinstalled during the valve job. I would look for incorrectly timed camshafts setting the cam position codes - which requires several hours with the cam setting tool - not just looking to see if the marks are lined up, and air leaks causing the fuel trim and AMM codes. The first place to look for problems is usually where a car was worked on last.