MAF codes

**Track Junkie** · 03-21-2014, 06:45 PM

Hello everybody,

This is my first post here and I have a question about a 99 Camaro SS that my son is purchasing. The car failed the emission test and the owner was told that the MAF needs to be replaced. The codes are P0102, P0103 and P0106.

First of all, does this sound like the MAF must be replaced and if so, should we go with the stock or a larger after market. What brands do you guys recommend and what is the expected gain in HP. There are a few good tuners here in St. Louis so we will most likely have the car tuned.

The car already has long tube headers, SLP air lid, LS6 intake and a mild cam.

Thanks for your input and help.

**98TransAmWs-6** · 03-21-2014, 08:48 PM

Originally Posted by Track Junkie

Hello everybody,

This is my first post here and I have a question about a 99 Camaro SS that my son is purchasing. The car failed the emission test and the owner was told that the MAF needs to be replaced. The codes are P0102, P0103 and P0106.

First of all, does this sound like the MAF must be replaced and if so, should we go with the stock or a larger after market. What brands do you guys recommend and what is the expected gain in HP. There are a few good tuners here in St. Louis so we will most likely have the car tuned.

The car already has long tube headers, SLP air lid, LS6 intake and a mild cam.

Thanks for your input and help.

P0106 is a code related to the MAP sensor and not the MAF. This is set when the PCM sees a rapid change in the MAP value but not in any other factors such as throttle angle and engine speed, which should change as well. The fix for this is typically a new MAP sensor which is located on the back of the intake manifold.

P0102 and P0103 are low/high output MAF error codes. A few things to check would be to first clean the MAF since a really dirty MAF can set codes and then check the connection and clean it as well. Once you have done that reset the PCM and see if the codes come back, if they do it is likely you have a bad MAF.

I would not go with an aftermarket MAF as extensive tuning is required and sometimes they still cause problems. If the MAF does indeed need replacement I would either get a stock replacement one or get your car tuned for Speed Density which gets rid of the need for a MAF all together.

Not sure on the gain numbers but you will only benefit so much if you still have the stock throttle body and intake manifold by going bigger with the MAF or going Speed Density. I deleted my MAF with Speed Density and personally I think it was the best decision since I no longer have to worry about it and it was cheaper than upgrading to a 102mm MAF to match with my 102mm TB and intake.

**Naaman** · 03-22-2014, 01:03 AM

I agree. Clean the MAF.

**Too Fast** · 03-22-2014, 04:29 AM

If you do replace the MAF, get an OE replacement. Too many people have been fooled into the aftermarket MAFs, and were sorry they did.

**pajeff02** · 03-22-2014, 05:43 AM

Do a visual inspection on the existing MAF -- it is has been de-bladed, de-screened or ported it needs to be replaced. I 100% agree that you should go with a stock GM replacement. It will have a plastic housing, rather than aluminum, may have an adapter harness, and probably will be 80mm (or 85mm ?) rather than 78mm, however, it is correctly calibrated for the car's PCM. Does the engine have a stumble in the rev range?

**Track Junkie** · 03-22-2014, 07:53 AM

Guys,
Thank you very much for all your input. We are picking the car up next week and the plan is to clean the MAF sensor and all the connections. I normally do all basic maintenance when I get a used car just to be sure everything is up to date. Once we do all that, I was going to take the car to Auto Zone or O'Reilly and see what kind of codes we are getting.

I am also not sure if the MAF sensor and the throttle body are stock or aftermarket but the owner claims that the car has a LS6 intake. You've mentioned the stock GM MAF is plastic so I will check for that. Is there a way to determine which intake (LS1 or LS6) is on the car. I guess the same question for the throttle body.

There is no stumbling at any speed but the car idles a little rough which I figured is due to the Cam.

Thanks again for all the info.

Regards,
Mike

**pajeff02** · 03-22-2014, 08:27 AM

The stock MAF is aluminum, the replacement MAF from GM is plastic.

This is a stock MAF that has been hacked up (not what you want to see!):

This is a GM replacement MAF with an adapter harness:

**Track Junkie** · 03-22-2014, 04:41 PM

pajeff02 Thanks for the clarification and the pictures. I am hoping that cleaning the MAF and the connections would take care of the codes but worse case, I'll replace the MAF.

**pajeff02** · 03-22-2014, 04:44 PM

Glad to help out.

**Naaman** · 03-22-2014, 11:50 PM

Now, since we're on the topic of MAFs, I just gotta know what the deal is with a MAF "upgrade." So, the MAF monitors air intake. Does an "upgrade" simply "lie" to the PCM in order to alter the air/fuel ratio to make more power? Wouldn't a tune be a safer (and surer) way to improve performance and combustion? What in the world would a "high performance MAF" even do (lets assume the rest of the engine is stock)?

**pajeff02** · 03-23-2014, 04:08 AM

Honestly, it is a bit of advertising hype. The stock MAF will support builds up to around the 500 hp level. Some aftermarket MAFs simply alter the signal to the PCM resulting in airflow being misreported on purpose so that the PCM will call for more or less fuel. Intentionally messing with the MAF will throw off its calibration and result in airflow being misreported - generally causing a lean condition.

**Track Junkie** · 03-23-2014, 06:07 AM

The GM part number that I found is 19207203 for the MAF from gmpartsoutlet.net
It's around $200 and seems to be the best deal for a new one.

**Naaman** · 03-23-2014, 11:12 PM

Thought so. Thanks for the clarification, sir.

**Track Junkie** · 03-29-2014, 06:14 AM

I ordered a new GM MAF and installed it yesterday. I also made sure all the connections and the air filter were clean. The old MAF was an aftermarket and it looked like it was messed with.

Took the car to O'Reilly and the car still shows the P0101 and P0102. The P0106 is gone. Any idea what needs to done next to pass emissions.

Thanks in advance for your help.

**pajeff02** · 03-29-2014, 07:04 AM

Did you clear the codes after installing the new MAF?

**Naaman** · 03-30-2014, 12:16 AM

Like Jeff is saying, it is important to clear the codes once the new part is installed. The computer doesn't check to see whether you've replaced the MAF. It just logs data and when it sees a certain pattern it either turns on or turns off the SES light. You could drive the car through a few drive cycles to see if the code clears, or you could just erase the codes and see if they come back.

If you did clear the codes and they came back, I'm thinking the connection could be bad (?) or else maybe a wire is bad (?).

Here's a random thought:

Could the IAT sensor have anything to do with it? If the PCM thinks the temp is X, then it would expect the MAF to have a certain reading, correct? If that reading doesn't jive, could the computer be fooled into thinking its a MAF issue instead of an IAT issue?

**SSNAKEATER23** · 04-02-2014, 10:44 AM

I had a similar issue, my intake sensor was reading incorrectly which caused my car to run lean. Maybe change the sensor, it could help.

**Track Junkie** · 04-02-2014, 11:02 AM

We had the codes cleared and ran the car for a minute and checked again and it is still throwing P0102 and P0103. The car feels like it needs a tune (starts to die sometimes while slowing down to stop at a red light) so I am eventually getting it tuned and I am wondering if a tune would get rid of these codes. I really can't think of anything else.

- - - Updated - - -

Originally Posted by SSNAKEATER23

I had a similar issue, my intake sensor was reading incorrectly which caused my car to run lean. Maybe change the sensor, it could help.

Are you talking about the sensor that plugs into the air lid?

**pajeff02** · 04-02-2014, 11:51 AM

The PCM does a comparison between measured and calculated airflow and if the difference is greater than a certain amount it trips a code. First thing to look for are any possible air leaks that could be feeding more air into the engine than is coming through the MAF. You'll want to check the intake ductwork after the MAF, the throttle body, and the PCV system. The PCV system is notorious for cracking at the adapter on the passenger side of the intake that houses the actual valve. You also need to check the hoses for the system as they wrap around behind the passenger rocker cover and then cross over to the driver side rocker cover. The MAP sensor is plugged into the back of the intake - tough to get to, but the grommet there is another potential leak. You could also just have a "bad MAF" and this can be tested by swapping a known good MAF onto the car temporarily.