Do I Need A Throttle Body Service

People have asked me if they really need a throttle body service. I have touched on this subject in past articles but today I will go a little more in-depth. In my opinion dealership service departments and auto repair centers are recommending this service way too much. When I took my car in for the Cadillac recall the service adviser told me I needed one.

throttle body clean

Clean throttle body

When I got home I removed the air intake hose and shined a flashlight into the throttle body. It was perfectly clean and almost shiny. It most certainly did not need to be serviced and cleaned. This is not to say that a throttle body service is never needed in fact I do believe they should be done as required.

This would mean a visual inspection to verify it is needed. Therefore if someone recommends this service to you I would ask them why do I need it. If they tell you, because it’s dirty I would then ask them how they know.

The correct answer to this question is they removed the air intake hose and performed a visual inspection. Or they scanned the vehicle and monitored the IAC (Idle air control motor) steps at base idle. If they did not do this I would not purchase the service or at least seek out a second opinion.

What does a throttle body do?

dirty throttle plate

Open throttle plate

The throttle body allows the driver to control the speed of the engine by controlling the amount of air that enters it. The driver pushes on the gas pedal and in the old days the cable would pull on the butterfly inside the throttle body assembly. Nowadays most of these throttle systems are what they call drive by wire.

You can ask Toyota engineers for more details on the system but Basically this means that your gas pedal is now a sensor that sends a signal to the throttle body about how far to open the throttle plate. Each type of throttle body assembly is designed to allow a certain amount of air to pass through it with a particular amount of throttle plate opening.

When the throttle plates are completely closed some air is still needed. This is where the idle air control valve or motor comes into play. The IAC valve meters a small amount of air into the intake manifold. The computer controls the idle air control valve and only allows enough air to keep the engine from stalling. This metering allows the computer to control the idle speed.

The IAC valve can be monitored on an automotive scan tool as mentioned above. How far the valve is opened is counted in steps. The dirtier the throttle body the more steps are required by the IAC valve to maintain engine idle.

Therefore you can actually use the steps to diagnose a gummed up throttle body. As an example if you observe on a scan tool that the IAC steps are around 50 this could be considered a little high. After a throttle body service is performed you would most likely see IAC steps at about half of that or below 25 steps.

How to service the throttle body

new throttle body

new throttle body kit

Modern vehicles are better equipped to compensate for a throttle body that is becoming dirty. So in my opinion the newer your vehicle and the lower your actual mileage, the less likely you need this service. On the flip side of this if you have a 1995 vehicle with 125,000 miles on it and you have never cleaned the throttle body I could just about guarantee that you need a throttle body service.

When carbon and varnish accumulates on the throttle plates or in the throttle bore the amount of air that can pass through into the engine can be reduced. Although this normally causes an idle problem these deposits can be cleaned off of the throttle body assembly and the airflow restored. It is quite possible that you could perform this service on your own in the driveway depending on your skill level.

The carbon deposits can be cleaned with spray type cleaners and wiped off with a cloth. The difficulty of the throttle body service depends on the application. In some cases the throttle body may need to be removed to properly clean the assembly. I use the very complete 3M Diy Fuel System Tune-Up Kit that comes with a DVD on how to perform the service. It is a three-step kit that includes a fuel additive to be installed in the tank.

To review you might need a throttle body service. If you take your vehicle in for regular maintenance or auto repairs chances are your shop will recommend the service to you. Ask them questions to verify that they really checked into it and are not just recommending it by mileage. I posted a video about engine stalling that shows how to do a throttle body service with the parts removed. Or you can use this next link to take you back to the auto repair information blog homepage.

18 thoughts on “Do I Need A Throttle Body Service

  1. Mark Gittelman Post author

    Alan: I can’t shed much light on this other than I have heard of the problem before. It seems replacement of the throttle body is the solution for internal failure of the non serviceable position sensor. Unfortunately I have never heard cleaning it to be successful. The problem is common enough that I have recommended customers contact GM to ask for assistance to retain customer loyalty. Unfortunately Pontiac is no more and the age of the car makes assistance unlikely.

  2. Alan Longstreet

    Hi Mark, I took my car (08 pontiac g6) in to clean the throttle body and they did that, however the problem (both reduced “engine power & traction control off” flash across the computer display) returned quickly and they insist I need to replace it. They don’t really seem to have any answers for why it needs to be replaced, only that the code said it should be cleaned, they cleaned and the problem returned — now it’s time to replace. Do you have any insight as to why a throttle body will ultimately fail?

  3. Mark Post author

    Don: The only way to know for sure is to remove the air intake hose and shine a flashlight into the throttle body to see what it looks like. Generally speaking I think this service is over sold as the throttle body and iac was designed to compensate for naturally occurring deposits.

  4. Don Bright

    Thanks Mark, this info is very helpful to me. I have a 2007 Chevy Impala and I do preventative maintenance at the dealer (Pat O’Brian Chevrolet) where I purchased the car. Each time I take my car in for service, they always come up with something that needs to be done.

    I did not agree to a Throttle Body Service, because I wanted to check this out, and I am glad that I did. Thank you for the informative information. Mark, I forgot to mention that my 2007 Chevy Impala has 49K miles. This is the vehicle that the dealership claims that I need Throttle Body Service. Tell me what you think?

  5. Mark Post author

    Michelle: The ” Is it worth fixing” is always a hard question to answer. A 2007 with 85k would seem to me worth saving. I do not know the details of this repair or your last one for 1200 bucks but I’m getting the feeling that exploring for a second opinion might be prudent at this juncture.

  6. Michelle

    I have a 2007 Saturn Ion with 85K miles on it. The check engine light came on and I took it to the dealer. They said I need the throttle and connection replaced. It’ll cost me $562 to fix. Is it worth fixing on a car with this many miles? My car has had another repair only 6 months ago…I had to replace the air pump and some other things related…that cost me 1200.00.

  7. Mark Post author

    Mary: I don’t blame you for being skeptical of the diagnosis since you already have $200 into not fixing the issue. I would call GM customer service ( the number in your owners manual) and ask for assistance with the problem. Since the vehicle is not to far out of warranty by miles and under the 3 years they can assist if they think it will turn you into a satisfied customer that will buy more GM vehicles. I would point out to them that you have already spent 200 bucks in misdiagnosed repairs. I would also mention that you feel the throttle body problem could represent a safety issue for you and your passengers. They might not cover all of it but they might help?

  8. Mary

    Mark, I have a 2011 Chevy Equinox and have been told I need to replace the throttle body. I took it into a Chevy dealer after the engine light came on and they replaced some wiring in the pedals, charging me $200. The next day, the light came on again. I took it back in and they are now saying that the body throttle needs to be replaced for about $400. They tell me my warranty doesn’t cover it because I have too many miles on it (46K). I purchased this vehicle to avoid having to spend big bucks like this for a least a few years. Could this possibly be part of a recall? Also I am not completely confident that the dealer is diagnosing the issue correctly. Any input from you is greatly appreciated.

  9. Mark Post author

    Michele: Not the first time I have heard of multiple repairs recommended to solve one problem. The interesting thing is if this was under warranty the factory would expect to see one failure for one problem. In your situation a call to GMC customer assistance would seem to be a good Idea. Ask for assistance and request an explanation if they refuse. It couldn’t hurt to let them know that your future as a customer is at stake. In other words if they help… You would continue to buy there product.

  10. Michele

    My 2002 GMC Envoy dashboard reads “stop engine”” oil pressure low””check gauges”. I have taken it to the GMC dealer too many times to count. The second dealer finally said it was the throttle body, so I got it fixed for $507. Back to the shop it went, twice after the same things came on the dash. Now they are saying it is the fan clutch, $847. I don’t believe it was ever the throttle body to begin with. Needless to say, I have not gotten it fixed yet. I am still steaming and trying to figure out if they charged me to fix something that was never wrong….if those lights go off after they fix that fan clutch then I guess I will have an answer, huh!!!!!

  11. Maygan

    Hi Mark
    Just wanted to update you Ford replaced the throttle body free of charge, just picked it up this morning and it’s driving so much better. Thanks for the info
    Maygan

  12. Mark Post author

    Maygan: P2112 is a Ford specific code that stands for “Throttle Control System Stuck Closed” So I am not surprised of the dealerships conclusion that the throttle body needs replacing. But I am concerned that this Ford dealer was unable to diagnose the problem until you handed them the Code. Not all dealerships provide the same level of service. With that said I think you should call Ford customer service and push for assistance on your own! I have seen this issue discussed on message boards to the point that it may be a known problem. If Ford has issued an auto service bulletin it is often easier to get assistance.

  13. Maygan

    Hi Mark, I have a 2009 Ford Escape with about 55,000 mi, it has been stalling when I accelerate after a stop and the power train light comes on. I’ve been taking it to Ford (5 times) and they couldn’t figure out what was wrong. Yesterday it stalled again but I had my own code reader so I was able to get a code P2112. I took it back to Ford with the code and had them look at it. They told me I have a bad throttle body and it’s not covered by my warranty. My dad says those don’t go bad and it should be covered under emissions. They said they were going to contact Ford to see if they can help with having it replaced. It sounds a little odd, just wondering what you think.

  14. Mark Post author

    Jennifer: Intermittent stalling can be one of the hardest problems to diagnose (so I feel for you). The reason for this is it can be caused by so many different things. On a 10 year old car with unknown maintenance history the list is even longer. After researching a little on the terms ” 2002 Toyota Camry engine stalling” I see that you are not alone. On several of the Toyota nation forum posts I saw a few people mention small vacuum leaks. To me this is what I find most often when it comes to a stalling condition. I don’t know if this is your problem but it’s worth mentioning to the dealer on the next visit. In my opinion the dealership is the place to go for such a problem but like anything it comes down to the person diagnosing the issue and their experience with it.

  15. Jennifer

    Hi Mark!
    I recently bought a 2002 Toyota Camry with 86k miles. I had it serviced at dealership and all checked out well besides a weak battery. I was going to lunch one day and as I approached a stop light I could feel my car skip or stutter and my engine and battery light flicker so when I reached the stop light it cut off and would not start. It finally started back up after about 10 minutes and auto zone’s machine said bad battery so I bought a new one. Drive it 2 days and it cut off while I was turning at a corner. It crunk back up after about 2 or 3 mins.

    Took back to Toyota and still could not find anything wrong Monday. Wednesday it was about to cut off but it caught back up and kept going but eventually cut off for few minutes. I’ve been told it could be my alternator or I need throttle service but have no clear insight of what it could be to avoid any more than I’ve had to put into this car. I wanted something good on gas to travel 60-80 miles a day to work which it is and was good price but I’m frustrated with it. I wanted something I could pay off quick but now I question if i should have gotten something else. Any feedback is greatly appreciated in advance.

  16. Rich

    Thanks Mark. I bought a used 2010 Corolla right around Thanksgiving w/approx. 35K miles. Took it in today for the 40K service. Air filters are “black and should be replaced”. They also recommend HVAC service and throttle body and fuel injector service/cleaning. Doing the air filters and 40K service…put off the other stuff for later in the month (trying to split it up around paydays). Sounds like I should do a little more research and ask some questions before I commit to the throttle body service. I hate taking the car to the dealer for service *sigh*

  17. Mark Post author

    CJ: It’s true that the throttle body is not often replaced. But I have done it more then once. Usually related to sticking throttle plates or drive by wire problems. With that said the vehicles I have performed this operation are still in our fleet providing good service. I do not think a bad throttle body is a sign of a bad vehicle or other problems on the horizon. ( Just my Opinion)

  18. cj

    Thanks, Mark, this is very informative. I have a 2010 GMC Terrain 4 cylinder/valve (i’m not quite sure what the word is). it has 41000 miles 99% highway miles. i put 25k miles on in past 9 months since buying this used at the dealership with 15k already on. it’s at the dealership today getting the throttle body replaced. from what I’ve read elsewhere, throttle body does not go bad? should i be concerned of bigger problems with time? my job requires a high reliability vehicle and I am concerned. wondering if i should turn it in sooner than i usually do (120K).

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