5 Signs of a Bad Transmission Pump

automatic car transmission pump on blank background

Transmission pumps move fluid through the gear system of automatic gas cars. They pull fluid in through a filter using a torque converter, then press it into the transmission, keeping the system lubricated and cool.

If a transmission pump fails, the system it supplies with fluid can suffer serious damage. Catching this problem early is the only way to avoid a major expense. As anyone who's had to replace a transmission system can tell you, it's no fun.

The good news is, transmission pump failures are fairly rare. The main reasons they break down are insufficient fluid (which can stem from a transmission leak), contaminated fluid (which can stem from clogged or defective filters), or worn-out parts elsewhere in the transmission (which is a problem in its own right).

The bad news is, if you have a bad transmission pump, you won't have much time to stop using your vehicle before the damage is done. So pay close attention to these warning signs to catch a struggling pump before it's too late.

1. Check Engine Light

check engine light

You don't get a ton of info from this light, since it can mean so many things. But if it comes on, you have at least some kind of mystery to solve.

If you have a diagnostic reader, you can take a peek into your car's brain yourself (PS—hey cars, maybe just put these codes on the dashboard for us to read).

If you don't have a reader or the light won't reset, head to a repair shop to have someone check it for you.

2. Leaking Fluid

Like an engine light, a fluid leak can mean several different things. Transmission fluid is only one possibility, but it's one of the worst-case scenarios.

If you notice a leak, identify the source as quickly as you can. If it turns out to be the transmission, take it into a garage promptly so they can seal it up before the rest of the system gets injured.

3. Burning Smell

This is a bad sign, and it's a little more specific.

When your transmission pump starts failing, it won't circulate fluid as it’s supposed to. As a result, the transmission will begin to overheat and the fluid will burn. The smell will be easiest to identify when you check the fluid dipstick, and the fluid itself will be darker than normal.

This symptom can also happen when your fluid levels are too low, so take a look for that, too, and make a habit of checking them as part of your maintenance routine.

If you do discover that your fluids are low, look for a leak.

4. Transmission Noise

When the gears and clutch packs aren't being lubricated by fluid being pumped into the transmission, the resulting friction will make a whining noise.

You might notice this even at regular speeds, but it'll get louder as you go faster. The noise will become increasingly obvious as the clutch parts wear down.

As much as you might like to, don't ignore it. The longer you wait, the worse things will get.

5. Difficulty Shifting Gears

hand shifting gears in car

When transmission gears run very low on fluid, they'll start to grind even more. This can make it physically difficult to shift gears, and it can cause the whole vehicle to experience jerky or hesitant motion.

Failing pump pressure can also make it harder for gears to stay in place. They might slip from one position to another, even jumping to a different gear seemingly randomly.

This is all very bad news.

If you notice these symptoms, take your car to a garage as soon as possible. The more you drive without addressing them, the worse (and more expensive) the damage will be.

As these problems get worse, a vehicle's motion will become less reliable. When a transmission fully fails, your car can stop moving altogether.


Unless you're an advanced mechanic, you'll probably need to take your car into a garage for these symptoms. They'll probably tell you that you need a new transmission pump, along with a new torque converter and filter. While they're making the repairs, they'll also want to flush the cooler lines.

As bad as this all sounds, the work should at least come in under $1,000. This is still better than replacing an entire transmission, which is one of the most expensive repairs a car can require.

So pay attention to these signs. If your pump turns out to be broken, they can save you from a big financial setback.