So I am getting three engine codes and I believe that they are related. The car runs fine but I am getting the 3 codes in the picture below. Is this an indication of a bad MAF? The car runs fine and gets decent gas mileage. Any input would be helpful.



And what is the difference between a current and pending fault?

 

OBD II has provisions that when a fault is detected it will store it but not immediately store the DTC and/or CES (check engine soon) light.

There are transient faults which are stored by the ECU for reference but will not trigger any CES. If within a defined time frame the fault clears, it will be deleted from memory, as the system is running normal. Sometimes it will look for the presence of the fault over a certain amount of time, sometimes a certain number of engine cycles which can be ignition switch ON/OFF or warmup cycles. It can take up to 40 cycles to clear certain faults by itself. This always requires the fault to be "NO LONGER PRESENT", else it will add to the counter and eventually go from "PENDING" to "CURRENT FAULT".

If the fault is showing up more times some faults have a counter which will store the fault permanently and eventually also show the CES only after so and so many times it triggers the fault. This is to avoid nuisance warnings. i.e. a misfire will usually only trigger after detection of so and so many misfires but not already the first time.

 

For the faults themselves:
Do you happen to have or have access to the GM service and more importantly to the electrical and diagnostics manual for your specific Blazer?
But I guess not else you would not ask here.

I'm assuming your Blaze is the 2000 of your build thread?

https://www.obd-codes.com/p0174
https://www.obd-codes.com/p0171

These could both indicate that a more generalized problem exists.

https://www.obd-codes.com/p0102

IMHO I would go figure:
The P0102 first, by checking on the MAF sensor itself. Connectors, cleanliness of the wire mesh, debris/objects.
Then go along all the air path for correct setting.
I would nevertheless start at the air inlet, air filter element and piping to the MAF, even if not directly related.
All upstreams of a MAF should not cause the faults you see, because all the air has to pass by the MAF and only there the quantity (mass) is determined. That's just to be thorough.

Make sure all downstream of the MAF is correctly in place. This includes all the vacuum lines. Make sure these auxiliaries do not leak somewhere away from the manifold. I had such an issue on my SAAB with the nearly exact symptoms. The leak was small enough not to cause driveability issues but to trigger the fault on the ECU intermittently. Fixed by replacing a set of vacuum hoses.

By the time you have cleaned the MAF and reached a leak free air intake until the cylinder heads you may have found the fault.
I guess that you have a good chance of finding a leak somewhere. If not there is further troubleshooting before replacing parts.

Others - please add and correct me. Maybe somebody has the diagnostic charts for the 2000 Blazer for the P0102.?

 

When it comes to "What does this code mean?", Kyle busted his butt putting together a 5 page thread explaining what the various codes mean and how to work with them.
Diagnostic Trouble Codes (DTCs)

 

I would bet money on a vacuum leak affecting mostly the passenger side cylinders (bank 2).

Codes list in order of when they presented themselves. In this case, since the B2 lean code is the only set code and the MAF low & B1 lean codes are pending, I would surmise that the MAF low code is a result of unmetered air entering the engine behind the MAF sensor and that unmetered air is entering the driver side of the intake manifold in the area of the PCV and other vacuum related ports. I say the driver side of the intake because the intake runners for the passenger side of the engine are located on the driver side of the intake plenum.

Have a look over all of the vacuum lines and if necessary, disconnect them and plug the ports on the intake to see if the problem goes away. You should be able to monitor the short term & long term fuel trims as well as idle air control counts to see if the problem goes away. IAC counts will be a quicker indicator. If you take note of the IAC counts, disconnect the HVAC/4wd vacuum line, plug the port, and notice that the IAC counts increase, then that would indicate that the problem is with that system of vacuum lines and further inspection is necessary.

Understand that disconnected lines will result in those functions dependent on the vacuum pressure will be disabled. This could include the functioning of the HVAC doors, the 4wd system, as well as the power brake booster if you disconnect the booster line. I put this warning in just so you are aware. I do not think you need to disconnect the brake booster feed, but if you do mistakenly, just be sure to check the brake pedal feel before you start driving.

I also doubt that the problem is the PCV valve, but stranger things have happened in the past. That one is easy enough to check, but be aware that there are two types of PCV valves out there. One that has a check valve (should rattle when shaken) and one that is just a drilled orifice (will not rattle).

You could also get a can of sensor safe carb cleaner and spray it around the vacuum lines, listening for a change in engine RPM. If you hear a change in engine RPM, then the problem is somewhere in the area you fogged with the cleaner.

 

My plan was to initially pull the MAF and clean it (with MAF cleaner) since all of the vacuum lines seem to be intact.

 

Cleaning the MAF shouldn't hurt anything, but I do not think that is the source of your problem. Again, given that the P0174 is current and the P0102/P0171 are pending, that would suggest a vacuum leak sooner affecting B2 which would mean that the leak would be somewhere on the driver side of the intake.

 

My plan is pull the intake tube off and check out the Driver's side of the engine.

 

@OP
You may also post the MAF reading value for idle. It could be compared with an expected value and give more clue than guessing...