Skip the auto shop - Our mechanics make house calls

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?

A: Hello there, thanks for your question. I&#3...

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?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Save up to 30%

Get a quote

What others are asking

Q: Getting code P0303

If you have already taken the first step of getting your codes scanned, the next thing to do would be to have an ignition test performed by a qualified technician. Attempting to do this yourself could result in being shocked...

Q: Repeated Fuel Injector Seal Failure

O-rings on fuel injectors have to be liberally lubricated with engine oil prior to installation. Installation is typically made with a twisting motion as you push the injector into the bore on the fuel rail. Be sure the aluminum surface...

Q: Check engine light and P1345 code

I'm thinking that they may have sold you a V6 distributor. Remove the rotor and look at the top of the vane cup for a "6" or an "8". It there is a 6, it's a V6 distributor and won't...

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...
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...
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...