Car Engine

Symptoms Of A Bad Or Failing Throttle Body

Mike Cross
Updated October 18, 2020

A throttle body plays a vital role in your vehicle’s performance. You find this component in vehicles with fuel injection. It is part of the air intake system, and it works by managing your vehicle’s air flow through the engine.

When the throttle body goes bad, you’ll know it. It is important to know what to listen and look for.  This will allow you to properly diagnose whether your throttle body is indeed the issue. You will typically find the throttle body positioned between the air filter box and intake manifold.

If you know where your mass airflow sensor is located, the throttle body is most often attached to it. Your engine needs to stay within a certain temperature range. And since the throttle body assists with this, an engine coolant line usually runs directly through the throttle body.

When everything is operating as it should, your engine will get the proper amount of air and fuel that it needs. Your vehicle will run like a top. But if it isn’t getting that perfect quantity, that’s when you’ll notice erratic engine behavior.

If you feel your gas pedal isn’t giving you the normal feedback when you press on it, there’s a good chance a bad throttle body is the culprit. Does your vehicle jerk inexplicably when you try to give it gas? Have you been dealing with a stalled engine as of late?

These are just a couple of signs that your throttle body needs to be inspected. It is of paramount importance that you address any irregularities sooner rather than later. You have much better chances if you fix the problem early. If you let it go too long without being serviced, it could damage your vehicle beyond repair.

Symptoms Of A Bad Or Failing Throttle Body
Symptoms Of A Bad Or Failing Throttle Body

Signs and Symptoms

So, with that being said, what are the biggest contributing factors that cause a throttle body to malfunction? Below, we’re going to take a look at some of these so that you can have your throttle body repaired or replaced as quickly as you’re able.

Irregular Idling

As mentioned, a stalling engine can be one of the biggest giveaways that your throttle body is on the verge of being shot. If it isn’t outright dying on you, but idling at a very low level, you should certainly have the throttle body looked at.

If you notice your vehicle sputtering out on you when you come to a stop sign or red light, it’s definitely time to take it to a trusted mechanic. This can also be true if immediately after starting the vehicle your gauge hovers at a low number.

The reason it’s doing this is due to the throttle body's plate opening and closing faster than it should. When this happens, you’ll often experience stalling.

Vacuum Problems

Directly related to the plate improperly opening is vacuum leaks. This means the airflow isn’t entering through the lines like it should, leaving fuel and air escaping out of the hose. Conversely, with vacuum problems, your engine will idle high rather than low.

This happens when too much air is let into your vehicle’s intake system. Pop your hood and stick your ear near the engine. If you hear a hissing sound emanating from that area while your vehicle is running, you’ve most likely got a vacuum leak.

This is a pretty straightforward fix that sees your vacuum hoses replaced. Once completed, your throttle body will continue to get the right amount of flow back into it. And hopefully, your vehicle will return to its normal behavior.

Gunk, Grime, and Goo

Anything that blocks fuel and airflow can cause major problems for the throttle body. Its metal casing and lines need to be as clean as possible at all times. This allows the mixture of fuel and air to pass through uninhibited.

Deposits of carbon can start to stick inside the housing, interrupting that perfect balance required to let your vehicle run well.

Any other form of debris that can potentially clog the lines needs to be taken care of right away. Similar to the snowball effect, the smallest amount of buildup can cause other grime and gunk to accumulate rapidly.

It’s a good idea to monitor this to the best of your ability and nip it in the proverbial bud before it gets out of hand.

Check Engine Light

Anytime the throttle body malfunctions, the check engine light will come on to let you know there’s a problem. This may be your first indication, as this light can come on well before you start to experience vehicle troubles.

If this happens, you should immediately check to see if any of the other symptoms we list are present. That way, you can remedy any potential dangers that could lead to bigger headaches down the road.

If using best obd2 scanner, you can get code P2119 or something similar when run diagnostic.

Auto mechanic dismantles the opposing engine for diagnosis
Auto mechanic dismantles the opposing engine for diagnosis

Mileage Discrepancies

Low idling may not be the only sign that your throttle body needs maintenance. Your vehicle may accelerate slower than usual, and you may notice that you just aren’t getting the same amount of miles per gallon that you once were.

This all goes hand in hand with improper fuel and airflow. You may even see that the connector to the throttle body has become corroded. If this is the case, consider removing the corrosion yourself before taking it to the shop.

To do this, you simply need to unscrew the air duct and do some minor cleaning. Compressed air is a handy way to remove buildup. You might want to grab some throttle body cleaner from your local auto parts store, but it may not be a necessity.

Just blow out any gunk with the compressed air and wipe away whatever comes out. Replace the air duct and start your vehicle. Check that it idles like normal, and give it a little gas to see if you get smooth feedback.

If that doesn’t do the trick, you may be looking at something more nefarious. In which case it may be best to get it to your mechanic for an evaluation.

Mike Cross
Life is too short to drive with stock audio

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