Skip the auto shop - Our mechanics make house calls

Q: How can I tell if it's the throttle body or the transmission at fault?

asked by on

while on the freeway i was trying to accelerate and it wouldn't. i got the throttle body cleaned. I've noticed before and after the shifts a little rough, meaning it jerks when shifting gears. i haven't noticed any burning smells, slipping of the gears or any grinding noises when the gear shifts. the rpm doesn't change too much. i have gotten the codes read when the check engine light comes on and it gives transmission and throttle body codes. i don't want to spend the money on another transmission if i don't have to.

My car has 130000 miles.
My car has an automatic transmission.

Hi and thanks for contacting YourMechanic. Check the fluid to the transmission, and look at the color of the transmission oil and see if it is red or dark red. If it is dark red (varnished), then change the oil and filter on the transmission. This can correct most shift issues. If you still continue to have harsh shifting, then either the transmission control (valve body) has a stuck valve or the accumulator has a broken spring and needs checking.

If you need further assistance diagnosing your vehicle, then seek out a professional, such as one from YourMechanic, who can come to your location to determine why the car is shifting hard and perform any needed repairs.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!
  1. Home
  2. Questions
  3. How can I tell if it's the throttle body or the transmission at fault?

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: how do you know if you need a whole throttle body compared to just cleaning it or replacing sensors

I would recommend cleaning and replacing the sensors first. Generally, throttle bodies do not need to be replaced completely, but rather just need specific parts related to them replaced. I would also recommend checking the mass air flow sensor to...

Q: When started it struggles to idle and cannot even rev.

Hello. This can be caused by a few different things. It can be a sensor problem, an internal engine issue, or just need a tune up. I usually start by scanning the computer for any codes. If there are codes,...

Q: Windshield leaking, how bad is this?

The leaks could be caused by improper sealing of the windshield, or possibly a blocked body drain. Has the windshield ever been replaced? Are there any rock chips at or near the sealing surface of the windshield? Something that you...

Related articles

How Long Does a Distributor O Ring Last?
The distributor is part of the ignition system in your vehicle and its purpose is to route high voltage from the ignition coil to the spark plug. The spark plug then...
P0052 OBD-II Trouble Code: HO2S Heater Control Circuit High (Bank 2 Sensor 1)
P0052 code definition HO2S Heater Control Circuit High (Bank 2 Sensor 1) What the...
How to Avoid Back Pain in a Car
If you have back problems, sitting in a car for an extended period of time can be excruciating. Even without back problems, you could experience discomfort and soreness from...