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: Do i really need to replace the ignition coil?

There are ways to test the output of the coil before it reaches the distributor cap. Usually, if there is a problem with a spark plug wire, spark plug, or distributor cap, the problem is consistent. Those parts can...

Q: Q: Engine turns over but won't start

The ignition coil, ignition control module, or distributor rotor can all fail without warning, leading to a no start. The reason I am leaning towards an ignition system issue is that the vehicle was running before you went to the...

Q: So I need a total tune up on my car! I was wondering if I could replace my spark plugs now and wait till next week to replace the coils?

Hi, thanks for writing in. Yes, that will not be a problem at all. If the coil is tested and is within spec there is no reason to replace it at all - I recommend using it. A fouled spark...

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 Heater Control Valve Last?
Keeping the right amount of coolant in a car is essential in keeping the engine at the right temperature. Failing to have the right amount of coolant or even bad elements...
P0240 OBD-II Trouble Code: Turbocharger Boost Sensor B Circuit Range/Performance
P0240 code definition Turbocharger Boost Sensor B Circuit Range/Performance What the P0240 code means P0240 is an OBD-II generic code triggered when the Engine Control Module (ECM) detects the intake boost...