In California, national auto parts store like AutoZone, Orielly’s, etc. are no longer giving free testing, they will not scan your vehicle at all. Why? Each Vehicle has a manufacture diagnostic procedure to follow.

For example:

scanner read: P0102 Mass Airflow (MAF) signal too low.
Tests/Procedures:

1. Check and verify that there are no vacuum leaks or unmetered air leaks.2. Check the MAF sensor grams/second readings as follows:
A. Idle (about 830 RPM) 3.5 grams/sec or more (4 to 4.5 grams/sec preferred.
B. 2500 RPM no load, 9 to 15 grams/sec (11 to 12 grams/sec preferred).
C. Wide open throttle road load (drive vehicle at 45 MPH in 3rd gear and perform a wide open throttle acceleration, observe maximum indicated grams/sec readings on the MAF) 90 or more grams/sec preferred.D. A MAF that exhibits consistently lower than normal grams/sec readings can cause a P0102 code to set.
The scan tool is the 1st step and only a guide to solving the problem.
What if the problem was a vacuum leak?

Does AutoZone have a smoke machine?

The scanner never tells you the Diagnostic procedure. If it was a vacuum leak and you skip all these procedures, and changed the mass air sensor, you have wasted your money and time.
These customers would blame the parts store and its “diagnostic Scanner” That’s why they no longer provide this service.

Victor B-
375 S Rancho Santa Fe Rd San Marcos Ca 92078
(760) 490-0487