Honda has a weak start

This is a 2003 honda civic with about 150k on it. Recently the check engine light came on so I went to Advance auto parts to get my codes read. I got back that the oxygen sensor had gone bad and each and every cylinder was misfiring?

What could be causing the each cylinder to misfire like that? I drive it about 60mi every
day and it doesn’t seem to drive all that rough. So it’s kinda weird that it said every cylinder was misfiring, like how could I even drive it like that?

I heard the oxygen sensor is something I don’t have to worry too much about. I could still drive it. The clerk told me to some spray carburetor cleaner on it and that should do something for it.

But recently I’ve noticed that it starts up rough, seems to strain for about 2-3 seconds then it starts.

Anyways, what do you guys think my next step of action should be?


The misfire will lead to ruining the cat and you’ll wish you would have replaced the O2 sensor. Also might be time for the general major tune up with plugs, wires, etc.

In addition to making sure the plugs and wires are up to date . . . if you don’t know when they were last done, they’re way overdue

Check the compression
Check the valve lash . . . it should be pretty easy to check and adjust on your car

Note . . . if the valve lash was tight for too long, you may have already burnt some valves

If valve lash is tight, you’ll have low compression, and it’ll be considerably more difficult to start the engine

Is your engine oil level good?

Check the fuel pressure also

You can rule out compression and oil level quickly

The other things may take a little longer

Wouldn’t a code reader pick up low oil levels?

"Wouldn’t a code reader pick up low oil levels?"
no, you check oil level with the dipstick. See the owner’s manual.

But of course, if the oil level gets too low, there will be a red light on the dash, but at that point, the engine is on the edge of major damage.

This thread just made me cringe. Please give your car the TUNE UP CARE IT DESERVES…Stay away from advice from the parts counter at any auto parts store. At the very very least…since you dont seem to know. Change the plugs…and see what happens…then move on to the coils or however your plugs are fired on this 03 Honda Engine…prolly coil over plug at that point.

Hondas do not ask for much…just a little love here and there.

Sometimes the absolute WORST THING a car can be is Reliable…then they get ignored and become sad and unhappy. That makes me angry…


This is the same OP that claimed a mechanic told him he could have water only ( no antifreeze ) in the radiator in the winter. This person needs to find a good mechanic and just do every thing the mechanic says. Or at least purchase a new vehicle with maintenance included.


Id say I just need some new spark plugs ive tested the coils which seem fine. The plugs would seem to make the most sense at this point.

At the VERY Least Jim… Be careful when you are removing your plugs however… you may need to work the wrench back n forth back n forth instead of just powering them out of their respective locations. Often I initially loosen the plug…spray some PB Blaster or WD40 down into the plug hole to let it soak down into the threads to help lubricate them. If your plugs feel stubborn coming out…DO NOT Rush them out…work them back n forth.

Keep in mind you have Steel plugs in Aluminum Threaded holes…it is a recepie for disaster when they dont want to come out smoothly… Just take your time and dont be afraid of using some kind of lubricant to help them out of their holes.

When you buy your new spark plugs…ALSO buy a bottle of “Never Seize” Compound to use on the threads of the new Spark Plugs. This stuff is basically powdered Zinc in a base of lubricating grease and it goes a long way to ensure you dont strip out your cylinder head…trust me…You Do NOT want to strip out your cylinder head!!

Just take it slow when removing the original plugs…dont be afraid to use lube,…and dont be in a hurry…its ok to work them back n forth a little so they dont strip out their threads… This is one area where a little time spent will actually pay dividends in the end. If you have ever had to retap all the spark plugs on a cylinder head you will know why I am writing all of this to you…it is not fun.


Nice catch Volvo. And a good suggestion.

To the OP, you’ve gotten a lot of good advice here. We ourselves have debated the use of “never-seize”, also called “anti-seize” on spark plugs. Some plugs specifically state on the box not to use anti-seize, so do the research. If you’ve taken the trouble to do the research, the use of anti-seize becomes a personal preference.

Also, I strongly recommend against the use of other than OEM plugs. I’ve done the research to find out who the OEM suppliers are for my car, NGK and Nippon-Denso, but you may want to ask the Honda parts window guy. Or just buy the plugs there. There are a lot of plugs out there that simply don’t work well in all engines.

You might also want to mark the cylinder numbers on the plugs when you remove them and post pictures. A lot can be learned from the condition of used sparkplugs.

There’s a random misfire code P0300 I think . That doesn’t mean every cylinder is misfiring each time. It just means there are multiple misfires and they don’t occur always on the same cylinder. If you Google “Honda P0300” you’ll see a link with a list of the most common causes. The way to figure it out, your mechanic has to go through that list one by one.

The faulty O2 sensor isn’t the cause of the starting problem. At least for cold starts. The O2 sensor reading is ignored by the engine computer until after the sensor warms up to its operating temperature. You can do the same thing as above, use Google to find the most likely causes of your O2 sensor diagnostic code. A faulty O2 sensor can be caused by something seemingly unrelated to the O2 sensor. A lot of good O2 sensors are replaced by folks seeing that code.

I’m not sure what effect spraying carb cleaner on an O2 sensor would be. Might help, might damage it. Don’t spray too much if you try it, b/c you don’t want raw carb cleaner going into the cat.

If any work has been done on your car using silicone sealants, those byproducts can damage O2 sensors.

Lots of great advice above. This one may prove tricky to get to the bottom of. If there are any routine maintenance items for the engine that you’ve postponed, this would be a good time to bring all that up to date. Might save you from some wild goose chases. Best of luck.

What have you done about the overheating and coolant loss? If nothing, you may have coolant entering the cylinders after shutting off the engine. This can cause a misfire/rough start condition.