Why Does An Automatic Transmission Have High RPM Before Shifting?


One of the most common problems with automatic transmissions is high RPM before shifting. This isn’t a worry if it only happens once, but a routine occurrence may lead to more issues, including frayed belts and scorched clutches!

If your automatic transmission has high RPM before shifting, it could be due to a leak, timing problems, or solenoid failure. When properly diagnosed, these maintenance issues can be fixed relatively easily if you know what to do.

In this article, I’ll discuss some common transmission issues that result in high RPMs before shifting and how to resolve them. Keep reading to learn how to detect issues before they spiral out of control.

6 Reasons for High RPM Before Shifting an Automatic Transmission

It can be difficult to figure out what’s causing your car to rev at high RPMs. However, paying attention may reveal some common symptoms that point to a solution.

Some of these symptoms might seem like a minor issue at first, but theyy often lead to something worse. Usually,it’s best to take your car in for a check-up to help find and fix the source of the high RPMs.

1. You Have a Leaky Transmission

A leaking transmission is one of the most common causes of high RPM before shifting. The transmission fluid is responsible for lubricating and cooling the gears. So, a fluid loss will cause the gears to slip, resulting in high RPMs. If this goes unnoticed, the transmission might fail. Fire is also on the menu as the red lubricant is highly flammable.

How To Fix?

If you have a leaking transmission, the first thing you need to do is fix the leak. You can do this by replacing the gaskets, seals, or O-rings in your transmission. You can also use a sealant or a stop leak product to fix the problem.

Once the leak is fixed, you need to flush and refill your transmission with new fluid. This will lubricate and cool the gears, and it will also help protect them from further damage.

Read: Why is My Car With Automatic Transmission Jerking?

2. Your Transmission Is Out of Sync

If your transmission is out of timing, it can cause the gears to slip and the car to rev at high levels. That’s because the gears will not mesh together correctly. And this problem is usually caused by a worn-out timing belt or camshaft. 

Having the gears out of sync can result in high RPMs. If this is not fixed, you could experience engine problems like knocking. You could also damage the valves in your engine. And these have far-reaching consequences that are best avoided whenever possible.

How To Fix?

If your transmission is out of timing, you need to replace the timing belt or the camshaft. You can also have a mechanic adjust the timing of your transmission, but this is usually a more expensive option.

Once the replacement is complete, you need to flush and refill your transmission with new fluid. This will lubricate the gears and keep them in sync.

Read: Why Your Car’s Transmission is Slipping & Fix

3. You Have Solenoid Problems

If you have solenoid issues, you may notice that your transmission is revving at high levels. The solenoids control fluid flow into and out of the transmission. And if they’re not working correctly, it can cause the gears to slip and the engine to rev high.

A dead battery or corrosion on the battery terminal may be causing the solenoid problems, or the solenoids could be worn out and need to be replaced. The tell-tale sign of solenoid problems is having trouble starting the car.

How To Fix?

If you have solenoid issues, the first thing you need to do is test the battery. You can do this by using a voltmeter to check if you can get a consistent 12 volts. If not, the battery is bad, and you need to replace it.

If the power pack is fine, the next step is to replace the solenoids. You can remove the valve body and replace the worn-out solenoids. This is a relatively easy fix that you can knock out in three hours or less!

Read: Why Speedometer Is Not Working and Transmission Is Not Shifting?

4. Your Clutch Is Worn Out

A worn clutch is prone to slipping, which results in high rev. That’s because the clutch is responsible for transferring power from the engine to the transmission. And if it’s worn out, it won’t be able to do its job properly.

A slipping clutch will need less and less pressure to engage, and it will eventually start to slip. This can cause the gears to be out of sync, making it hard for the engine to transfer rotating power to the transmission.

If this is not fixed, it could eventually lead to transmission failure. So, if you’re noticing that your car is revving at high levels, it might be a sign that you need to get your clutch replaced.

How To Fix?

If you have a worn slipping clutch, the best thing to do is replace it. This can be a costly repair, but it’s better than letting the problem get worse.

However, replacing a clutch is not an easy DIY job. It’s best left to a professional, as many things could go wrong if not done correctly. Still, we’ve seen petrol heads who can swap a clutch in under 5 hours!

Read: Car Full Service Cost // Whats included?

5. Vacuum Hose Leaks

Traditional cars come with lots of hoses under the hood. And if one of these hoses is leaking, it can cause the engine to rev at high levels. This is especially true if the vacuum hose, which is responsible for transferring air from the engine to the transmission, breaks.

A broken vacuum hose can also result in multiple mechanical issues, including misfires and a total system shutdown.

How To Fix?

If you have a vacuum hose leak, the best thing to do is replace it. You can do this by removing the transmission cover and replacing the hose. Once it’s replaced, check to make sure that there are no other leaks. Your tranny should be running smoothly after that.

However, if you’re still experiencing problems, it might be a sign that you need a new transmission.

6. You Might Be Looking at Faulty Speed Sensors

If the speed sensors in your car are faulty, your car may not shift gears properly. This is because the speed sensors tell the transmission when to shift gears. If they are not working correctly, your transmission may shift gears too soon or too late.

The sensors are usually located near the differential on the car. They are small, cylindrical objects with a wire coming out of them. And you can check to see if they are working by taking your vehicle for a drive and watching to see if the check engine light comes on. 

How To Fix?

Speed sensors are usually not very expensive, and replacing them is a job that most people can do themselves. You only need to remove a couple of screws to get to them, and then you can unplug the bad one and plug the new one in its place. Just be careful not to touch the wires while working on them, as they can shock you.

You will also need to go beneath the car and check the wiring. If the wiring is damaged, you will need to replace or fix it. 

Read: Car Diagnosis Cost


There could be a number of reasons for high RPMs before shifting an automatic transmission. For instance, if your car slips or stalls out, it might be a sign you need a new clutch to bring down the RPMs. Or, a vacuum hose leak usually requires replacing to bring back the much-needed balance to your drive train and result in normal RPMs.

In general, be sure to drive safely and be aware of your surroundings. Remember, high RPMs can be dangerous, so it’s best to avoid driving the car until a qualified person solves the problem.

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