I had a MAF sensor replaced on my 2000 sonata. How do i reset the computer so I con pass emmisions test

The best thing to do is, remove and clean all the sensors and connectors I have listed below.

A code P0125 may mean that one or more of the following has happened:

• Insufficient warm up time
• Low engine coolant level
• Leaking or stuck open thermostat
• Faulty coolant temperature sensor

Possible Solutions The simplest thing to do is to reset the code and see if it comes back.
If the code comes back, the problem is likely going to be the result of the above causes (faulty thermostat, faulty ECT sensor, or a low coolant level).
Other ECT sensor and circuit related DTCs

A code P0171 may mean that one or more of the following has happened:

• The MAF (Mass Air Flow) Sensor is dirty or faulty
  Note: The use of "oiled" air filters may cause the MAF to become dirty if the filter is over-oiled. There is also an issue with some vehicles where the MAF sensors leak the silicone potting material used to protect the circuitry.
• There could be a vacuum leak downstream of the MAF sensor
• Possible cracked vacuum or PCV line/connection
• Faulty or stuck open PCV valve
• Failed or faulty oxygen sensor (bank 1, sensor 1)
• Sticking/plugged or failed fuel injector
• Low fuel pressure (possible plugged/dirty fuel filter!)
• Exhaust leak between engine and first oxygen sensor

Possible Solutions A lot of times, cleaning the MAF sensor and finding/fixing vacuum leaks fix the problem. If you're on a tight budget, start there, but that may not be the fix for certain. So, possible solutions include:

• Clean the MAF sensor. Consult your service manual for it's location if you need help. I find it's best to take it off and spray it with electronics cleaner or brake cleaner. Make sure you are careful not to damage the MAF sensor, and make sure it's dry before reinstalling
• Inspect all vacuum and PCV hoses, replace/repair as required
• Inspect all hoses and connections in the air intake system
• Inspect and/or test the intake manifold gaskets for leakage
• Check for a dirty fuel filter and proper fuel pressure
• Ideally you'll want to monitor short and long term fuel trims using an advanced scan tool

co2 sensor/s and egr might need cleaning.

Hi Paige, Have the thermostat replaced and then see what happens. It sounds as if the engine temperature is the problem you have remained with, that's not to say the mass air flow sensor were not defective. Regards John

Resetting the computer isnt going to fix anything. Get it repaired. If you reset it, it still will not pass if the monitors have not run and passed.

in the inlet air pipe from the air filter to the manifold

Borrow or change the MAF completely,you have a LEAN combustion condition.The MAF could very well be the problem as it is the most common source lean combustion.
You will need a catalytic converter in good shape.

Do a engine tune up this should solve the problem.

take negative cable off for 5 minutes and then put it back on it should reset it

Hi:

We failed our emissions test as well, and went to the dealer to get the o2 sensor fixed. When I was paying the cashier told me that after such work, the car needs to drive for a while so the computer can confirm there are no problems, otherwise it sends out a code saying it's not ready to be checked. I was told 2 or three days.

A couple of things that I would recommend (just some suggestions) would be to clean the MAF sensor, I believe you indicated that sometimes it shows fault. Also maybe just disconnect the battery for a day maybe two. If all else fails find someone that lives outside of a stinking emissions testing area and use whatever means necessary to register your car there. In all seriousness the emissions is a bunch of BS and the technician is/was being truthful. The vehicle does need to be driven a certain # of miles for the computer to re-set but my limited understanding is usually 150-250 miles MAX. If you are running short on time depending on where you live, you may also want to go to the tag office and see if they can give you a waiver or an extension, I would probably take it elsewhere and have another emissions place check it out. I hope some of this may help you out.