# Throttle position sensor for 2001 Altima



## Ognacho (Jul 18, 2018)

Does anyone know if a 2001 Altima is equipped with an electronic throttle position sensor. Does it have to be relearned/reprogram after performing a throttle body cleaning (TBC). Prior to cleaning the engine would started to bog down when I accelerated. I decided to clean the MAF, change the fuel filter/air filter and clean the TB. I did disconnected the electrical connections on the TB before removing it. I did manually open the throttle plate to clean the interior of the the throttle body. After cleaning all the components I started the car and the RPM when up to 2000. When I depress the accelerator the car would start to bog down and stop running. Not sure what happened. Prior to the car bogging down it was running great. The Service Engine Soon light was on and the code was P0402. Appreciate any help.


----------



## smj999smj (Jan 1, 2006)

No, not the type of throttle position switch that you're thinking of. It's held onto the side of the throttle body with two bolts. When replacing, there is a specific adjustment procedure for it required and the closed throttle position switch has to be re-learned. Consult the FSM if you replace it; NICO Club's site has free, online factory service manuals.








P0402 is an EGR code. If you cleaned the throttle body on the engine and spray cleaner into the engine, it will tend to start (initially) like a flooded engine. Erase the codes and take it for a good ride and see if the codes re-trigger before digging into them.


----------



## Ognacho (Jul 18, 2018)

smj999smj said:


> No, not the type of throttle position switch that you're thinking of. It's held onto the side of the throttle body with two bolts. When replacing, there is a specific adjustment procedure for it required and the closed throttle position switch has to be re-learned. Consult the FSM if you replace it; NICO Club's site has free, online factory service manuals.
> View attachment 5997
> 
> P0402 is an EGR code. If you cleaned the throttle body on the engine and spray cleaner into the engine, it will tend to start (initially) like a flooded engine. Erase the codes and take it for a good ride and see if the codes re-trigger before digging into them.


Thanks for your quick response and help. I'm a 75 year old DIY, my Altima 2001 for the most part is a good running little car and like me it needs a little tender care. 

Just so I an clear. The throttle position sensor on my 2001 Altima, opens the butterfly plate in the TB when the gas pedal is depressed. The sensor has two electrical connector on the side of the TB (which I disconnected) The only information I could find on you-tube for TB was for a 2002 and newer. This type does require the TB to be relearned. After completing maintenance on my 2001 and the rpm surged to 2000 I was lost. I didn't find anything on 2001 so I am glad I when to the "Forum"

I did spray TB cleaner in the intake manifold and clean it as far as I could reach. Plan one...I will try erasing the code and take it for a ride. One question, once I erase the code and start the car and the rpm surge to 2000. Should I wait for the rpm's to return to normal ie (750 rpm). What if the rpm do not come down? What's next?

I looked up the NICO club and found a long list of PDF files. Do you know what PDF file covers specific adjustment procedure to relearn the TB switch that you mentioned, if plan one doesn't work.

Thanks for the help. Ognacho


----------



## smj999smj (Jan 1, 2006)

Your throttle position sensor doesn't open the throttle plate; that would be a throttle actuator system used on the 2002 Altima. When you press your gas pedal, it operates a throttle cable, which attaches to a throttle drum on the side of the throttle body. As the cable pulls the drum, it turns the throttle shaft which causes the throttle valve (or, "butterfly valve") to open. The end of the throttle shaft turns a lever in the throttle position sensor, which uses variable resistance to affect the voltage signal being sent to the ECM. By the amount of voltage sent to the ECM, it determines how open the throttle valve is. 
One of the harness connectors on the throttle position sensor is for the throttle position sensor, itself. The other connector is for the closed throttle position switch. 
When adjusting base idle, the engine needs to be fully warmed up. Run the engine at 2000 RPM for 2 minutes and then let it idle. Shut off the engine and unplug the throttle position sensor. Start the engine and rev it a couple of times and then let it idle; it will be in "timing set mode." Now is the time to adjust the base idle using the screw on the IACV-AAC valve (which can be seen if you look down between the #1 and #2 intake runners, IIRC). Also, ignition timing is to be adjusted to spec at this time, as well. Once done, turn off the engine and reconnect the harness connector to the TPS. If, while adjusting the idle during this method, it can't be lower or raised to spec, it may be possible that the IACV-AAC valve is bad; also, inspect for other issues such as vacuum leaks, improper fuel pressure, etc. After timing and base idle have been adjusted, the closed throttle position must be re-learned. While this should be done "properly" with a scan tool to be sure the closed throttle switch position has been learned, you can usually get it done by simply turning the ignition switch to "on" for several seconds and then "off" for several seconds, repeating this procedure about 12-13 times.

These procedures are in the "EC" section pdf file, for "Engine Control."


----------

