# 2015 Hyundai Sonata can't go over 50 mph **URL:** \ **Category:** Maintenance/Repairs\ **Created:** [October 19, 2023, 9:23pm UTC](https://community.cartalk.com/t/2015-hyundai-sonata-cant-go-over-50-mph/193463 "2023-10-19T21:23:11Z")\ **Posts on this page:** 15\ **Page:** 1
**Author:** ![lydia\_185631](https://avatars.discourse-cdn.com/v4/letter/l/74df32/32.png) [@lydia\_185631](https://community.cartalk.com/u/lydia_185631)\ **Post date:** [October 19, 2023, 9:23pm UTC](https://community.cartalk.com/t/2015-hyundai-sonata-cant-go-over-50-mph/193463/1 "2023-10-19T21:23:11Z")
We have a 2015 Hyundai Sonata. Since two days ago, the engine revs up loud and it does shift gears. But there is very little power. The top speed is less than 50 mph. When stopping at lights, the idle is very high. Any suggestions what might be the issue(s)? Just trying to get an idea if this is something major or minor. Thanks in advance. ---
**Author:** ![Mustangman](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/mustangman/32/44130_2.png) [@Mustangman](https://community.cartalk.com/u/Mustangman)\ **Post date:** [October 19, 2023, 9:25pm UTC](https://community.cartalk.com/t/2015-hyundai-sonata-cant-go-over-50-mph/193463/2 "2023-10-19T21:25:35Z")
Is the check engine light on? Flashing? ---
**Author:** ![George\_San\_Jose1](https://avatars.discourse-cdn.com/v4/letter/g/e5b9ba/32.png) [@George\_San\_Jose1](https://community.cartalk.com/u/George_San_Jose1)\ **Post date:** [October 19, 2023, 9:31pm UTC](https://community.cartalk.com/t/2015-hyundai-sonata-cant-go-over-50-mph/193463/3 "2023-10-19T21:31:15Z")
Checking for diagnostic codes is the first step. My guess however, the exhaust system is clogged, possibly the catalytic converter. Cross your fingers that’s not the problem, b/c cat replacement is pretty expensive. ---
**Author:** ![lydia\_185631](https://avatars.discourse-cdn.com/v4/letter/l/74df32/32.png) [@lydia\_185631](https://community.cartalk.com/u/lydia_185631)\ **Post date:** [October 19, 2023, 9:31pm UTC](https://community.cartalk.com/t/2015-hyundai-sonata-cant-go-over-50-mph/193463/4 "2023-10-19T21:31:42Z")
The check engine light has been on intermittently for the last four months. CEL not flashing. It’s automatic. About 140k miles. I read a similar post. Looks like to get the code read first at an auto shop. Anything we should check before going to the auto shop? ---
**Author:** ![lydia\_185631](https://avatars.discourse-cdn.com/v4/letter/l/74df32/32.png) [@lydia\_185631](https://community.cartalk.com/u/lydia_185631)\ **Post date:** [October 19, 2023, 9:36pm UTC](https://community.cartalk.com/t/2015-hyundai-sonata-cant-go-over-50-mph/193463/5 "2023-10-19T21:36:20Z")
We did read the code back in July. The code was P0128. But this speed issue is only 2 days. So should we read the code again? ---
**Author:** ![George\_San\_Jose1](https://avatars.discourse-cdn.com/v4/letter/g/e5b9ba/32.png) [@George\_San\_Jose1](https://community.cartalk.com/u/George_San_Jose1)\ **Post date:** [October 19, 2023, 9:42pm UTC](https://community.cartalk.com/t/2015-hyundai-sonata-cant-go-over-50-mph/193463/6 "2023-10-19T21:42:15Z")
> [@lydia\_185631](#): > > code was P0128. But this speed issue is only 2 days. Not sure if this is related. Could be related. The P0128 suggest the coolant might not have been reaching full temperature. If so, more gasoline is injected to compensate for cold coolant, and the extra gasoline could possibly have caused a cat failure. ---
**Author:** ![weekend-warrior](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/weekend-warrior/32/26122_2.png) [@weekend-warrior](https://community.cartalk.com/u/weekend-warrior)\ **Post date:** [October 19, 2023, 9:49pm UTC](https://community.cartalk.com/t/2015-hyundai-sonata-cant-go-over-50-mph/193463/7 "2023-10-19T21:49:39Z")
Maybe this… [MC-10152858-9999.pdf (nhtsa.gov)](https://static.nhtsa.gov/odi/tsbs/2018/MC-10152858-9999.pdf) It says… The vehicle can continue to be operated for a limited time in Limp Home Mode, but it will accelerate slowly and have a reduced maximum speed with RPMs limited to approximately 1800-2000 RPM. ---
**Author:** ![Mustangman](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/mustangman/32/44130_2.png) [@Mustangman](https://community.cartalk.com/u/Mustangman)\ **Post date:** [October 19, 2023, 9:59pm UTC](https://community.cartalk.com/t/2015-hyundai-sonata-cant-go-over-50-mph/193463/8 "2023-10-19T21:59:09Z")
No, just don’t get it checked at an auto parts store. Take it to a real mechanic. By the way, the check engine light means… The car needs service! ---
**Author:** ![lydia\_185631](https://avatars.discourse-cdn.com/v4/letter/l/74df32/32.png) [@lydia\_185631](https://community.cartalk.com/u/lydia_185631)\ **Post date:** [October 19, 2023, 10:09pm UTC](https://community.cartalk.com/t/2015-hyundai-sonata-cant-go-over-50-mph/193463/9 "2023-10-19T22:09:55Z")
We will schedule to have it checked out. Thank you all. ---
**Author:** ![davesmopar](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/davesmopar/32/41750_2.png) [@davesmopar](https://community.cartalk.com/u/davesmopar)\ **Post date:** [October 20, 2023, 1:21am UTC](https://community.cartalk.com/t/2015-hyundai-sonata-cant-go-over-50-mph/193463/10 "2023-10-20T01:21:18Z")
> [@Mustangman](#): > > By the way, the check engine light means… The car needs service! 100% agree… Just to add a little to what Mustangman said, you only have one CEL and 100’s of different things can cause it to come on, but the CEL does not change or get brighter or anything when another code shows up, so always best to fix the CEL issue, so you will know of another issue if it comes up… Not to mention, not fixing one thing could cause other things to fail prematurely, kinda like a snowball effect… ---
**Author:** ![LoudThunder](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/loudthunder/32/27769_2.png) [@LoudThunder](https://community.cartalk.com/u/LoudThunder)\ **Post date:** [October 20, 2023, 8:08pm UTC](https://community.cartalk.com/t/2015-hyundai-sonata-cant-go-over-50-mph/193463/11 "2023-10-20T20:08:13Z")
You have received a lot of wonderful advice, I hope you follow it. I would ask that after you get it really analyzed and serviced, let us know what the findings were and what was fixed and if it’s not too personal, how much it cost… Remember, you are anonymous with the user name of “lydia\_185631” ---
**Author:** ![lydia\_185631](https://avatars.discourse-cdn.com/v4/letter/l/74df32/32.png) [@lydia\_185631](https://community.cartalk.com/u/lydia_185631)\ **Post date:** [October 26, 2023, 5:43pm UTC](https://community.cartalk.com/t/2015-hyundai-sonata-cant-go-over-50-mph/193463/12 "2023-10-26T17:43:41Z")
So the diagnosis includes ECVVT Cover (NTHW) and Actuator (NTHW). Even when the mechanic tried to explain, it’s like a foreign language. Something about brushes…They said it took them 4 hours to figure out the problem. The diagnosis, the parts, and the labor combined is about $800. Does this make sense? Could anyone explain in plain English what the issue is? ---
**Author:** ![Cavell](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/cavell/32/43396_2.png) [@Cavell](https://community.cartalk.com/u/Cavell)\ **Post date:** [October 26, 2023, 6:56pm UTC](https://community.cartalk.com/t/2015-hyundai-sonata-cant-go-over-50-mph/193463/13 "2023-10-26T18:56:07Z")
You paid 800 and problem is fixed? ---
**Author:** ![lydia\_185631](https://avatars.discourse-cdn.com/v4/letter/l/74df32/32.png) [@lydia\_185631](https://community.cartalk.com/u/lydia_185631)\ **Post date:** [October 26, 2023, 8:26pm UTC](https://community.cartalk.com/t/2015-hyundai-sonata-cant-go-over-50-mph/193463/14 "2023-10-26T20:26:21Z")
Yes. It is back to normal. The CEL is off…so far. ---
**Author:** ![George\_San\_Jose1](https://avatars.discourse-cdn.com/v4/letter/g/e5b9ba/32.png) [@George\_San\_Jose1](https://community.cartalk.com/u/George_San_Jose1)\ **Post date:** [October 26, 2023, 8:42pm UTC](https://community.cartalk.com/t/2015-hyundai-sonata-cant-go-over-50-mph/193463/15 "2023-10-26T20:42:14Z")
> [@lydia\_185631](#): > > Even when the mechanic tried to explain, it’s like a foreign language. Suggest to Google the words or abbreviations your mechanic provides that you find the confusing. Mechanics use specific technical jargon, just like other professions. They do this to communicate with each other briefly & accurately. But the customer car-owner isn’t expect to know what it means. I have no idea what it means either just by looking at it, but Googling “Hyundai ECVVT Cover” turned this TSB up straight away, should be helpful. > **[SB-10090818-5448.pdf](https://static.nhtsa.gov/odi/tsbs/2016/SB-10090818-5448.pdf)** > > 1010.98 KB > [@lydia\_185631](#): > > Something about brushes… “VVT” means variable valve timing. A function your engine uses to achieve both good power and good economy (mpg), so it is a useful thing. This function is a common failure item reported here, on many makes. The forum search feature will show you what others have posted, link upper right this page. In summary, an electric solenoid – a type of electro-magnet – is used by the car’s computer to actuate this function. The actuator is rotating when the engine is running, so they had to figure out a way to connect the battery to the rotating actuator. Stationary brushes rubbing on a rotating commutator is a common way that’s accomplished. In days of electric-motor yore, the the brushes really looked like small paint brushes, the bristles made of fine wire. That’s why they are called ‘brushes’. The bristles would wear out too fast, so somebody invented another method, using short carbon sticks, which is probably what yours uses. i.e. your " brushes" don’t actually look like brushes, more like a short black stick. The VVT function can become highly problematic if the engine oil & filter changes are deferred, or the wrong oil spec is used. Suggest in future to ask your shop to change the engine oil and filter more often than the manufacturer’s recommendations.