Can A Bad Or Nonworking Oxygen Sensor Cause An Engine Misfire

Posted in Crank, Oil and Piston

I recently replaced the two O2 sensors before the catalytic converter and my car started shaking. I took it to a ‘reputable’ mechanic shop and they performed a tuneup to fix the misfire on cylinder 6. They tested the coils, changed the spark plugs, etc. and couldn’t fix the problem. I scanned my car and the codes I got were that the knock sensor is malfunctioning (this is not causing the shaking, for sure). I got the oxygen sensors codes which I fixed already, but I still got the code that said that there was no activity on sensor 1, bank 2., and the misfire code on cylinder 6. At the shop, they told me that the problem might be the computer, which I think is very unlikely. I notice that they are strongly based on what the scanner tells them, which is never good for a mechanic shop. They were just guessing. They checked the wires that are connected to the cylinder 6 and found that it is not having enough electricity (the bulb they plugged was flashing dimly.) What might be the problem?
The wires that are connected to the cylinders are not the spark plug wires, though.

’98 Infiniti i30

There are 6 Answers for "Can A Bad Or Nonworking Oxygen Sensor Cause An Engine Misfire"

    1. The Plunja says:

      Its a bad mechanic problem go to another one, and as far as the car goes change the wiring harness to all 6 coils and double check the oxygen sensor it might be faulty or the wiring is loose.

    2. bobweb says: ^( ^(

      Don’t forget that dealer technicians see problems like yours day in and day out because all they work on is your manufacturer’s car. They’re factory trained. So you pay for the expertise you get. You might as well go where the best chance of fixing the problem is which may be your dealer.

    3. jeffyukon says:

      The misfiring cylinder is causing the “no activity” dtc related to the 02 sensor as when a cylinder misfires,there is alot of oxygen in the exhuast because the fuel did not burn.That is what sets a no activity code as the 02 sensor will read a lean condition due to the misfire.If the noid light was installed to the #6 injector harness and only flashed dim,you most likely have a bad connection in that circuit between the injector and the engine controll module.Get a schematic and check the resistance of both those circuits.You could also temporarily switch injector harnesses to make another harness fire #6 and see if the misfire changes cylinders,you may need to use a jumper harness to do this. If the resistance checks out good,you may have a weak driver for #6 injector inside the engine control module.

    4. grande alacrán says:

      You need to post the codes next time it helps. ^( ^(

    5. texasm says:

      A knock sensor code is a P0325. It is usually accompanied by a P0340, since the knock sensor will not cause your warning light to come on. It will set a code, but is designed not to throw up a check engine light. The knock sensor retards or advances your timing based on engine noises, which will throw up the P0340 for the camshaft positition sensor. This will make the warning light come on. When your timing is being retarded by the knock sensor, YES, it can cause your engine to shake. I agree that some shops rely too much on codes, but it doesn’t sound like the shop is way off when they say it could be the ECM. You don’t automatically change the ECM, simply because a tech thinks that is the problem. There are ways to test the ECM, trace wiring, and test each component. The same goes for the oxygen sensors you replaced, relying on the code. Maybe they weren’t bad, if you still have the same codes. If it were me, I would look for what all of the codes have in common. O2 sensor, P0306 misfire on #6, knock sensor, engine shaking. Any reputable mechanic would be looking at the #6 and #1 fuel injectors. But that’s just me. I am not sure by what you mean ‘they checked the wires that are connected to cylinder #6 and found there is not enough electricity’? Not enough spark, or the voltage to the coil, is not high enough? This would cause a misfire at #6 if the coil isn’t getting the proper voltage from the ECM. This is quite possibly why they said it could be the ECM. The way to test the ECM is getting a grid sheet that shows all of the pin #’s and what their voltages should be and whether the testing should be done on individual pins with the engine on, or with the key on engine off. You have to check all of the powers and all of the grounds, and if any of them are not present, or out of range, that is a bad ECM. So no, the ‘reputable’ mechanic isn’t far off, but he did put the cart in front of the horse thinking a tune-up would fix a mis-fire.

    6. danigirl says:

      As for the actual problem itself I have no clue….SORRY!

      But I would bet there is a problem with the computer!!! I have a 97 Nissan (same company as Infiniti) and I have had lots of trouble with the sensors and computers! I couldn’t even register my car because of the problem I was having. So I had some of the senors replaced to try and fix the problem. The check engine light went off so I figured I was all set. When I took it back to be tested it failed again because the computer would not reset itself after it had been fixed. I did some looking online and found that these cars (97-98 especially ) are notorius for this problem. I had to put my car through a complete “drive cycle” several times before the computer actually reset…..and finally was able to get it registered.

      A month later though the check engine light is back on. Good for me registration is good for 2 years where I live – and I hope to get rid of the car by then!!!

      Good Luck!