[Maraz52]

Hi,
I have a 1998 Honda Civic EX that has 125,000 miles on it. It started with a random misfire cylinder 1 code. We did a tune up: replaced spark plugs with NGK's, good spark plug wires, and replaced distributor cap and rotor. Car worked better for 2 days, then misfired on cylinder 1 and 2. We bought some Sea Foam and put in gas tank, thinking we had bought some bad gasoline. Worked good for about 2 days, then random misfire on all 4 cylinders and ignition module failure showed up when codes were read at Auto Zone. We replaced ignition module. Again, 2 days later, misfiring started. Went back to Auto Zone and got more Sea Foam. We unplugged the sensor by the throttle body and reattached it. Can has been running better since then. What else should we check? It had a 1399 error code but I don't remember the other codes. We had replaced the fuel filter also.

[taco99mud]

I used to work at a Honda dealership in Lebanon NH. This is a quick fix, bring the car to your local Honda dealer and get your PCM re-installed. The computer got confused and messes with the timing on the car. The re-install will fix everything and only cost 1 hours worth of labor.

[TxGreaseMonkey]

Try resetting the ECM by pulling the Backup Fuse in the under-hood fuse box, or disconnecting the negative battery terminal, for 10 seconds. Record any radio codes first.

[Maraz52]

It has been a while but it is still acting up randomly. We get it checked, added Seafoam cleaner to gas and it works for a few days. Usually random misfire cylinder 1. Took it to Honda dealership and they said computer said I need to replace catalytic converter. I drove it a few times with warning light flashing. Is there an underlying problem I need to find before I replace the catalytic converter? Also, is it necessary to put the Honda catalytic converter on it? They are telling me the tuneup we did was no good because we didn't use their plugs and wires. Please advise. Also they wouldn't reprogram the computer, told me that was only a quick fix.

[Maraz52]

We finally got an error code for catalytic converter. Had garage replace with an aftermarket catalytic converter and they also replaced the oxygen sensor. Worked fine yesterday when I drove it to work. Hope this fixes it.

[stevens722]

We finally got an error code for catalytic convertor. Had garage replace with an aftermarket catalytic convertor and they also replaced the oxygen sensor. Worked fine yesterday when I drove it to work. Hope this fixes it.

How has the car been running since then?

[Maraz52]

It always ran OK for a few weeks after everything we did. Next replaced distributor. Still a problem. We finally replaced the fuel injector #1, which was the most frequent misfire code. Car is working OK now. Mechanic cleaned the other injectors when he replaced injector #1. this was last month, running OK so far, keeping my fingers crossed!

Replacing the catalytic converter and O2 sensor was not the answer evidently but was a costly expense for me.

[jose8107]

I have a honda civic 98 ex . I'm getting random misfire what u recommend me to do

[TxGreaseMonkey]

jose8107, replace the Ignition Control Module (ICM) and coil:

https://www.askmehelpdesk.com/cars-t...tml#post265896

[meanshell89]

I have a 1998 Honda Civic that I just purchased a month ago. The whole month it has ran great, but starting 2 days ago I have been having the same problem. Diagnostics said cylinder 1,3, & 4 are misfiring and some code that said " 02 sensor heater circuit bank 1 sensor 1". We have not replaced or repaired anything yet since we do not know what to start with. I did check out the spark plugs and they look fine. ANY IDEAS??

[TxGreaseMonkey]

meanshell89, start by replacing the oxygen sensor. Then, clear all codes and see if that doesn't solve the problem.