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2004 Hyundai won’t go over 20mph

Hyundai Accent

When I start the car it drive okay until it warms up to operating temperature then it won’t go over 20mph. It is a 2004 Hyundai Accent manual.


The check engine light codes will help guide you in the right direction. Without the codes you are pretty much just guessing. My thoughts are you have some kind of failed sensor. The reason is the engine is in a closed loop and uses preset parameters to function until it warms up. At this point it no longer uses the preset parameters and relies on the engine sensors. A faulty sensor or reading from a sensor it casing the ECM to go into LIMP mode. This is for safety reasons and will continue to function this way until the proper repairs are made. If you have the engine codes, post them below in the comments.

3 thoughts on “2004 Hyundai won’t go over 20mph”

  1. Not all codes that are stored will cause the check engine light to illuminate. However they are stored and can be extracted with a scan tool . If you do not have one, just about any local auto parts store will pull the codes for FREE. They might also try to sell you some parts but hey, they are an auto parts store after all.

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