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Throttle Control Warning Light: What It Is, and What to Do About It

By Stephen Fogel, August 1, 2018

Unless you drive a car that’s more than 30 years old, your gas pedal probably isn’t actually attached to the throttle. These days, it’s all electronic — and that means that when something goes wrong with the throttle, you’ll see a warning light on your dash.

If your vehicle has a specific warning light for the throttle control system, it’ll look like a lightning bolt with reversed parentheses on each side. If it doesn’t, you may see a wrench light or the check engine light instead.

The throttle control warning light will normally light up briefly each time you start your vehicle, and then go off. This is nothing to worry about. But if the light stays on, or comes on while you’re driving, your car needs some love. 

Let’s take a brief look at how the throttle control system works, or you can skip ahead to learn why the warning light can come on and why it's a bad idea to keep driving when it's lit. 

About the throttle control system 

For most of the 20th century, throttle control involved a direct, mechanical connection between your accelerator and the engine.

But as emissions control and fuel economy regulations became more strict, computers were developed to provide more precise metering of the air-fuel mixture that goes into the engine. 

In the late 1980s, “drive-by-wire” throttle control systems emerged. These systems replaced mechanical cable-based throttles with sensors that sent signals from the gas pedal to the engine computer. They’re much more reliable than the old cable-operated systems — but things still can go wrong. 

Why the throttle control light comes on

Because your throttle control system is complex, there are many reasons why your throttle control warning light can come on. Some might be obvious, while others might be hard to track down. 

If your car accelerates irregularly and you can’t seem to control it, pull off the road immediately and shut it off. Have it towed to a certified repair shop — it’s not safe to drive.

Since you’re dealing with a key system, any problems must be correctly diagnosed and fixed. Your mechanic has extensive experience with throttle control system trouble and can resolve these issues.

» LEARN MORE: Get an estimate for a throttle body replacement

Intermittent loss of throttle control

Because the connection between the gas pedal and the throttle is electrical, any disruption of the signals coming from the pedal will affect its acceleration. The throttle may operate properly at some times, but not at others. 

Solution: Stop driving your vehicle and have it towed to your mechanic. There, the first step will be to scan the engine computer for a trouble code. This should point your mechanic in the right direction. If there is no code, then a check of the sensors, relays, and wiring in the system should identify the problem. Repair and replace any troublesome parts. 

Sudden drop in fuel economy

You notice an abrupt drop in gas mileage, requiring more frequent fill-ups.

Solution: The throttle control system controls the air-fuel mixture that your engine burns. If it starts sending the wrong signals, it can inject way more fuel than is needed. The associated trouble code should identify a problem with the throttle controller, which can then be repaired.

» LEARN MORE: Get an estimate for a new throttle position sensor 

Hesitation or stumbling when accelerating

If the throttle control system gets damaged, erratic operation may cause a stumbling or hesitation when you try to accelerate

Solution: Don’t drive your vehicle in this condition; have it towed to your mechanic. After checking for any computer codes, your mechanic will repair the throttle control system, replacing or repairing parts as needed.

Engine stuck in limp mode

You’re unable to accelerate beyond a fast idle and are limited to very low-speed driving.

Solution: This indicates a serious failure of your throttle control system. The engine computer is programmed to go into limp mode when the system malfunctions, in an attempt to limit your speed and prevent damage to the engine. It can be caused by a sensor failure, or even by outside electromagnetic interference. Your mechanic can diagnose and fix the problem. 

Get it diagnosed by a professional

Can I drive with the throttle control light on?

Yes, usually, but you should go straight to a repair shop. There can be many different causes for the throttle control warning light, so a proper diagnosis is key. 

When the warning light comes on, there’s a possibility you either won’t be able to accelerate or you won’t be able to stop accelerating. Either of these situations could be extremely hazardous to you and your passengers. If your vehicle is running at all erratically, pull over and have it towed in.

 

2 User Comments

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By , December 18, 2017
I have an 07 Jeep Compass and my electronic Throttle control light came on a month ago when i was at a stop light, it shut my car off. I turned it back on and it was fine after that. My car drives ok but i noticed that this only happens when I am at a stop waiting for the light to change, why would this happen?
By , May 12, 2018
I have a2008 Ford expidition the throttle light comes on when my car drops out of gear into an almost dead stop it slams around like the transmission is going to drop out what’s going on

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