would that alone put the check engine light on?

I wanted to post the same thing: "tell us what you're getting and we can help figure it out"...right?

Then this:

And we know that this is just a mess of a car, various 'mods'... and really no plan to fix it, just somehow- anyhow- get a smog cert, so they can beat it into the ground for two more years.



I'll bet someone wanted a race car and put on oiled air filters and now the MAFs (mass airflow sensor) is shot.

IME, the DME is driven to add fuel to the mix, as the MAFs become fouled (the sensor is 'insulated' by the contamination and reports lower airflow to the DME than is actually occurring- the DME sees the O2 derived AFR and has to 'correct' by adding fuel trim...then it reaches its limit and you get an AE or AF "air fuel adaptation" code.

But really, all total speculation without those two codes that the op just didnt think were worth paying attention to....

Possibly but it is difficult to say without the actual code and the brief description on reader will typically guide you in right direction as to where to look to resolve issue. As an example, with regards to your MAF issue, it could be as simple as an air leak, possibly a tear in the air intake boot.

Again, as others have pointed out, without the actual code we are looking for a needle in a hay stack. If you are located near Valencia I'd be willing to pull the codes for you and clear them with my scan tool, however they will re-appear (possibly within the same day or week) until you have them corrected. I'm not implying that clearing the codes without correcting the issue(s) will get you to Pass your smogh check.

PM if you would like to take me up on my offer.

FYI, in case you don't know, clearing the codes will generally not allow you to pass the smog check due to the readiness flags in the Emissions control/OBD=II firmware/software.

MONITOR READINESS STATUS

Readiness flags are indicators on a scan tool or code reader that tell you when an OBD II system monitor has run or completed its test. A scan tool may say "ready" or "Complete" next to a listed monitor if it has run, or "not ready" or "incomplete" if it has not run. Others display a little flag or dot to indicate when a monitor has run.
If all the OBD II monitors have run, the OBD II system is ready. Ready for what? Ready for an OBD II emissions test or an I/M 240 or ASM loaded mode emissions test.
The emission test rules require that OBD II run most or all of its self checks BEFORE a vehicle is tested.
Why? So people don't use a scan tool or code reader to clear codes just before the test so they can pass the test.
If all the monitors have run and are ready, it guarantees an honest and accurate emissions test. And if all the monitors have run and are ready -- and OBD II has NOT found any faults, the MIL lamp is OFF and there are NO CODES in memory -- it means the vehicle should be in emissions compliance and pass any type of test it is given (OBD II, I/M 240 or ASM).
For 1996 through 2000 model year vehicles, the EPA emissions test rules allow up to two (2) readiness monitors NOT to be set when the vehicle is tested. Why? Because many vehicles require quite a bit of driving before all the monitors will run and be ready.
A short trip to an emissions test center may not involve enough driving or the right driving conditions to set the catalyst monitor and/or EVAP monitor (which are the two hardest monitors to complete because they require specific operating conditions before they will run).
On 2001 and up model year vehicles, all monitors must be ready before the vehicle can be given an OBD II test (rules may vary somewhat from one state to another). Exceptions may also be made for certain vehicles that have known readiness issues.

Here's the code. This time only one code came up, 3 months ago there were 3 of them. So it seems it is MAF, the shop told me to replace the whole box, which is around $450 + labor, but how do I know if cleaning it, replacing the sensor or as you said replacing the air intake boot wouldn't do the job?
Thanks.

Generally shops like to replace, not clean, things as replacement is a sure fix while cleaning may not work, e.g., if they try cleaning it and it doesn't work, people are unhappy to pay for the cleaning.

I would try cleaning it myself and then clearing the codes to see if i comes back. A Google search will lead you to may DIY's for cleaning MAF sensors. CRC makes a specific spray can cleaner for MAF and most full-line auto parts stores, such as NAPA, sell it.

Buy CRC Mass Air Flow Sensor Cleaner 05110 at Advance Auto Parts

It's worth a try, but be VERY gentle as most MAF sensors are rather fragile.

You can also check the air intake boot/path for any obvious cracks or air leaks, although I would generally expect a different code if it was an air leak problem.

P.S. Here's a nice summary of the code P0102:

OBD-II Trouble Code: P0102 Mass Air Flow (MAF) Circuit Low Input

P.P.S. If the stock air filter was replaced with an oiled air filter, such as a K&N, there is a good chance the MAF is contaminated by excessive oil from the filter.

Thank you.
BTW, I don't have an air filter, replaced it with CAI many yrs ago, so I guess that possibility is out. Stupid question, where exactly is the MAF located? also, where is the sensor? can it be easily accessed?
Thanks!

** You do have an air filter **
That's what Penguin was telling you - Your CAI (probably a K&N) could be causing your problem. When you service your CAI you coat the filter with a spray (oil) that attracts dirt. That oil may make it's way to your MAF and coat the sensor over time. IMO - The K&Ns and alike are not worth the time or money.

despite my posts, I am glad the OP is getting some assistance.

Agree with these comments- DO keep in mind that not all MAF sensor contamination can be cleaned: over time, the heat at the sensor film can lead to oxidization of the contamination layer- so while you can use CRC cleaner to get residue off, the crusty oxide remains. HOWEVER, if it improves with a cleaning that points you in the correct direction.

If you go to any of the large online auto parts places (rockauto, pelican, autohauz, etc, etc) you should be able to find a maf sensor (NOT the whole housing) for under 100. A pliers and screwdriver. (This is my guess, never worked on that model) 15 minutes..

It would be MOST helpful to hear the other two codes......

Holy do I agree with this.