sure you can clear the codes at an autozone or something but the car has to go through it's drive cycle before he can go for the test or he'll fail because the system's not ready.

go to autozone, post the P____ code on here -which'll probably be the knock sensor or the egr temp sensor, both common problems- but let us know the code, then get them to clear it, he needs to put at least 50-100 on it, then IF the light doesn't come on as soon as the system's ready again, he can try to squeak through the emission's test.

if it was 95 and older car (obd) you could just disconnect the negative off the battery and wait 5 minutes.