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Throttle body cleaning/replacement

My fiance has an 03 nissan Pathfinder, and the service engine light has been on for some time. she took it to the dealer and the code indicated a problem with the throttle body. They want $450 to fix it, and we are getting married soon and don’t have that kind of money now. I have been looking online to see if other people have had this problem with this car, and how it can be fixed. Some suggest that this can be done at home. My question is, if I am a fairly inexperienced weekend mechanic who has not worked on a car for several years, is this a task I can undertake myself? It sounds like I can try to clean the throttle body, as carbon tends to build up there, then go through some processes to reset the ECU, and throttle learning. Is this easy to do? Is there a chance I can royally screw something up? Please help.

It would be helpful to know the exact code or codes that were pulled. A lot of throttle body assemblies also incorporate the IAC (Idle Air Controller) and TPS (Throttle Position Sensor), and is a junction point for a lot of vacuum lines. Problems with any of these can set the Service Engine light, and may not be fixed with a simple throttle body cleaning.

However, a throttle body cleaning can help driveability problems when a lot of carbon has built up. The easy way to check is to disconnect the intake hose, open the throttle, and look down the opening. If the backside of the throttle plate is caked up, and lots of carbon-laden sludge on the throat, it could probably stand a good cleaning. Just use a sensor-safe throttle body cleaner so you don’t damage the sensors.

There are no codes for the throttle body itself. There are codes for those components mounted on the throttle body. Do you have the code number?


There are independent shops which will do an “intake tract cleaning” which includes the throttle body, idle air control valve passages, and the MAF (Mass Air Flow) sensor for about $75. If they ask you if you want a “fuel injection system cleaning”, ask if that would be to clear a particular DTC code; if not, there isn’t a good reason.

I should probably mention that the car does not start. It turns over and sounds like its going to start, and then it just dies. This has been happening on and off for a couple weeks. Its like the engine is not getting fuel. I don’t know the exact codes because she took the car in. I guess it will not hurt to clean the throttle body, and then reset the ECU, and do the accelerator, throttle valve, and idle air volume learning procedures

Yes, the not starting is an important aspect. Cleaning the throttle body and resetting codes will no fix this. The codes are very important, and would be the first step in trying to fix this. Otherwise, your shooting in the dark and wasting time and energy.

You state the engine will not start/stumbles and dies.
Have you tried depressing the throttle about halfway to see what happens?

Just wondering if this is an Idle Air Control Valve problem or a large vacuum leak. The IAC is a vacuum leak although it’s a controlled one; or supposed to be anyway.

It would really help, a lot, to know what the code is.
Generally speaking, removing and cleaning throttle bodies and Idle Air Valves is not that complicated a job and if you’ve got a bit of general wrenching experience you should get through it pretty easily.

Although I didn’t expect cleaning the throttle would work, it did! There was a mild build up of gunk on the flapping part and the sides. I cleaned it real good and put it back on with a new gasket, and reset the ECU, and throttle learning procedures, and it started right up idling around 700RPM after warming up. Strange.

I would try some Chevron Techron fuel additive. If you are into ethenal which can corrode. Follow the instructions. Worked on our 98 Lincoln. (two tanks of fuel with additive) Performing better than ever. Cheaper than mechanics bill!