2K Maxima Engine Light On but no code found

2 weeks ago my service engine light came on, I took my 2K Maxima to the service station he did all test and found no codes.
I drove the car next week and within few days the light came back on, I took it back to the same place since I had paid $89 already they checked again and found no codes.
They suggested I take it to the dealer, it might be a faulty PCM.
Please advice if I can do before I take it to the dealer.

Thanks.

...They suggested I take it to the dealer, it might be a faulty PCM. Please advice if I can do before I take it to the dealer.
Thanks.

If u know your screwdriver and r willing to check, read this page 14 and also p.10 ... http://www.cardomain.com/ride/748507/14

All starts from verifying healthy charge voltage 13.8V or more. Buy a 10$ multimeter to check. I had a multimeter hanging on dash (connected to cig lighter) to catch this intermittent charge light, no codes = check out the 2k2 alternator swap story on page 23