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AutoTech08, Workshop owner
Category: Car
Satisfied Customers: 973
Experience:  Diploma in Automotive Engineering, 30 years working experience.
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2000 Hyundai Accent: The Check Engine light was on

Customer Question

I have 2000 Hyundai Accent with 155000 miles on it. The "Check Engine" light was on. I checked for the codes and found out three things. I have a cylinder 2 misfire, random / multiple cylinder misfire, and main catalyst below threshold (bank 1). What do these codes mean and what can I do about them?
Submitted: 8 years ago.
Category: Car
Expert:  AutoTech08 replied 8 years ago.

Hi there,


You have the following codes?


P0300 = Random misfire detected. The engine is misfiring

P0302 = Cylinder # XXXXX misfire detected. Cylinder # XXXXX was first detected.

P0420 = Main catalyst below threshold (bank 1) . Catalytic converter is working lean.


Possible causes are insufficient fuel getting into the system..

1, Faulty O2 sensor.

2. Clogged fuel filter.

3. Vacumn leakages. Check for dislodged vacumn hoses, faulty PCV.

4. Faulty spark plugs.



AutoTech08 and 5 other Car Specialists are ready to help you
Customer: replied 8 years ago.

What can I do to fix these problems?

Expert:  AutoTech08 replied 8 years ago.

Hi there,


Check the fuel filter first, if it is clogged, replace it.

Check the spark plugs as well.

For vacumn leakages, check all the hoses to see if any is broken or dislodged.