Q: Check engine light won't shut off, problem in ECU

asked by on

Firstly, thank you for guys so much! Okay, so my car has a check engine light that goes on and off randomly, but mostly on (side note: I don't know if this is relevant but when the check engine light is on, when I start the car and then let out the clutch, the rpms drop like it is going to stall for a second, then runs perfect. When it's not on the car starts very loudly and stays at 1,500 rpms like it should) The code the check engine light is giving is an error with the CAM shaft sensor, but, after replacing the sensor two times with two different mechanics (I made sure they got the sensor from the Hyundai factory) we ruled out it actually being a problem with that. Then my mechanic looked for wiring problems, and after a week of work, he decided it was a problem in the ECU. There is nothing wrong with my car other than the light being on and it doesn't effect my preformance at all, and a new ECU is $1,100 to replace. I was wondering if there is a less expensive way to fix this? Thx!

My car has 106000 miles.
My car has a manual transmission.

You’re very welcome.

If you’re getting a code for the cam sensor, this doesn’t always mean the sensor is the problem. You may have a problem with slack in the timing chain or belt causing the crankshaft and camshaft sensors to not be in sync with each other. This would account for the engine to idle low and then jump up. If indeed the ECU has failed, there is unfortunately no way around it, and it just needs to be replaced. You could try checking with the dealer to see if there is a software update available for the ECU that could solve this issue. The best solution at this time would be to have a qualified technician, such as one from YourMechanic, come out and start the car cold and see if the engine timing chain is making noise at that time, and perform any additional diagnosis for this problem.

Was this answer helpful?
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
  1. Home
  2. Questions
  3. Check engine light won't shut off, problem in ECU

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: P0755 & P0700 error codes

The problem with buying used tires and not having them balanced is the potential problems they can cause. Most transmissions - or more specifically, the Powertrain Control Module (PCM) which controls the transmission and drive line - contain incredibly...

Q: Car jerking when switching gears

The illumination of a dashboard warning light means that a vehicle system has detected a fault. In many cases, the vehicle can be scanned for fault codes and data concerning the system. Your symptoms lead me to believe that there...

Q: How do I unlock the car with the smart key?

The smart key allows you to unlock your vehicle without using the key. Here’s how to use the unlock feature: 1. Make sure the smart key is on your person, such as in your pocket. 2. Press the button on...

Related articles

How Long Does a Distributor O Ring Last?
The distributor is part of the ignition system in your vehicle and its purpose is to route high voltage from the ignition coil to the spark plug. The spark plug then...
P0052 OBD-II Trouble Code: HO2S Heater Control Circuit High (Bank 2 Sensor 1)
P0052 code definition HO2S Heater Control Circuit High (Bank 2 Sensor 1) What the...
P2428 OBD-II Trouble Code: Exhaust Gas Temperature Too High Bank 1
P2428 code definition A P2428 trouble code signifies that the PCM has detected a problem in the exhaust gas temperature sensor circuit in bank 1, which subsequently contains the number one...