Q: Check engine light P0302

asked by on

My check engine light came on which produced a P0302 error code. I swapped out the engine coils in cylinder 2 & 4. I cleared the codes and started the car and ran it for a little bit. Now it is throwing P0304. So this tells me the engine coil is bad and should be replaced. If I have to replace one (I have 110,000 miles on the car), should I go ahead and replace all of them or will I be safe just replacing the 1? Also, what about spark plugs in these cars? Should they be replaced or are they good for the lifetime of the car?

Hello there, thanks for your question. I’d be happy to help. It does sound like a bad ignition coil is the cause of this P0302 trouble code. This is not uncommon since your car has over 100,000 miles. If it is just one coil causing the issue, then you should simply replace that one coil. Over time, the other coils will fail but that can be over a period of weeks, months, or even years. In my personal opinion, it is not worth changing them all if they are not bad. As for the spark plugs, they should be replaced at 100,000 miles. By not replacing them, the coils will work even harder which will cause them to fail prematurely.

If you would like help inspecting this or replacing the ignition coil, consider having an expert automotive technician from YourMechanic come to your home or office to make the necessary repairs for you.

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 P0302

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: Engine Light/ Maintenance Required/ TCS Light on

All these codes point to engine misfires. You should pull the spark plug wires to see if oil is on the spark plug wires causing the misfire. You would need to replace the valve cover gaskets and spark plug tube...

Q: Car misfires when the weather is cold and while idling

Hello. Thanks for writing in about your 2000 Lexus SC400. It may be necessary to replace all of the ignition coils in addition to having the ignition coil wiring inspected for damage in order to determine why your engine is...

Q: Car turns on and runs fine when cold but when warms up it randomly turns off

This is a common sign of a faulty ignition coil. Ignition coils are coated with a varnish-like insulation that becomes brittle over time after being stretched then contracted repeatedly The insulation develops small fractures that open when heated and close...

Related articles

How Do Power Car Windows Increase Passenger Safety?
Power windows are responsible for approximately 2,000 emergency room visits every year. When a power window closes, it exerts enough force to bruise or break bones, crush fingers, or restrict an airway. Though...
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...