I need the name of a tool.

P0101....Mass or Volume Air Flow Circuit Range/Performance Problem
P0121 - Throttle Position Sensor/Switch A Circuit Range/Performance Problem.
P0420 - Catalyst System Low Efficiency
there is criteria that enable trans shift
solve codes problems then transmission will shift normaly

P0101 ISUZU - Mass Air Flow Circuit Performancehttp://engine-codes.com/p0101_isuzu.htmlForum CodePossible causes- Dirty mass air flow sensor
- Dirty mass air filter
- Mass air flow sensor harness is open or shorted
- Mass air flow sensor electrical circuit poor connection
- Intake air leaks
- Faulty mass air flow sensor
Tech notes Before replacing the mass air flow sensor, try replacing the air filter and cleaning the air flow sensor with low compress air or mass air flow sensor cleaner. Reset code and drive vehicle. If the code comes back, it may be necessary to replaced the mass air flow sensor

THE INTAKE AIR TEMPERATURE SENSOR IS MOUNTED IN THE INTAKE AIR HOSE OF THE AIR CLEANER .THE INTAKE AIR TEMPERATURE SENSOR IS INTEGRATED INSIDE THE MASS AIR FLOW SENSOR.SHOULD BE NO PROBLEM REMOVE.DISCONNECT ELECTRICAL CONNECTOR,THEN REMOVE THE MOUNTING SCREWS HOLDING IT IN PLACE.THEN REMOVE IT.TAKE THE OLD INTAKE AIR TEMPERATURE SENSOR WITH YOU TO THE AUTO PARTS STORE SO THEY WILL MATCH UP AND GIVE YOU THE CORRECT SENSOR.WHEN YOU INSTALL NEW SENSOR,YOU NEED A CODE SCANNER TO ERASE CODE TO TURN OFF CHECK ENGINE LIGHT.

the mass air flow is located on the outside of the air box. this is where you put the air filter. undo the clamps that hold the hose onto the air box and to the throttle body. undo the bolts that hold the air box in place and remove the air box. there are 2 small bolts that hold the mass air flow to the box remove these and reinstall in reverse order. heres a couple pics to help you identify it. hops this helps

mass air flow sensor is located on the air intake duct right past the air filter, u need to release the two clamps that hold it in place. use either a 7 or 8mm socket, this would be in a 1/4 inch drive, or can also use a regular blade screwdriver, depending on clamp. after loosing clamps remove electrical wiring connector by depressing the release tab, push in first and then pull out. pull air intake hose off and remove sensor from air cleaner assembly.careful not to pull wires. but pull rubber grommet from housing so wires will pass through

3.8L Engine To Remove:
MAF Location

1. Disconnect the battery ground cable.
2. Remove the fuel injector cover.
3. Disconnect the mass air flow (MAF) sensor electrical connector.
4. Remove the MAF sensor mounting screws.
5. Remove the MAF sensor from the throttle body.

To Install:

1. Position the MAF sensor on the throttle body.
2. Install the MAF sensor mounting screws. Tighten the mounting screws to 27 in lb (3 Nm).
3. Connect the mass air flow (MAF) sensor electrical connector.
4. Install the fuel injector cover.
5. Connect the battery ground cable.

Remove the two screws that hold the MAF on the intake near the air filter, go to an auto parts store or electronic supply place and get a can of spray electronic cleaner, spray the inside of the air flow sensor, you need to get it into the small opening where the platinum sensor wires are, they get coated with dust and other gunk and confuse the computer because it gets the wrong signals,clean the wires until the look shiny, reinstall it, you may be able to clear the check engine light by disconnecting the battery and waiting 10 seconds, also replace the air filter and you should be good to go. ------- Check fig:--
Mass air flow sensor. Located in the intake near the airbox. 2 screws hold it in. Thanks.

Removing air box and tube leading to air flow sensor. Should just be a few screw like clamps. Make sure to hook wires back up exactly as removed. very easy replacement

Take it back until they fix the problem. This is the problem the dealer said it was, so let them have the hassle of figuring out why it's causing the mass flow sensor to test bad or be defective. My question is, Did they replace it in the first place or try to just clean it. You can buy a mass air flow cleaner from your local auto store and try cleaning yourself, which I think that may be the case they did.

Sometimes the mass air flow sensor will become clogged with some miniscule particles of dust or whatever else. When you open up your hood somewhere near where the air filter box is, there will be a hose running from that to the engine, the mass air flow sensor should be somewhere in near there. They are easy to remove and should be held in place with a few screws. Make sure not to touch any of the electrical connectors on the inside or allow them to get dirty. I used mass air flow sensor cleaner from the local parts place but it is a bit pricey. There may be some alternative cleaners available that are not as expensive. Take the sensor to a relatively dust free area and spray it all over with the cleaner and allow to dry. At the same time under the hood where the sensor was spray that area as well. Once the sensor has dried out re-install it and you should notice an improvement. If the problem still persists you may need to change your spark plugs, or spark plug wires.