About a week ago my CEL came on, I checked it and it threw code 0505 "No Failure Recorded/Detected". I reset it and drove on happy On Saturday I washed my car & engine bay (Simple Green & water) I covered up all electrics but not the knock sensor (didn't know what this was). Then yesterday my CEL light came on again and I got code 02 15 "Undefined", and 03 04 "knock sensor". I reset the light and my CEL blinked when I started it, I heard this means the engine is misfiring I got code 03 04 again. I just reset the CEL and will see what happens, it did not come back on or flash this time. The engine seems to be running fine and I think I feel a little lag in performance, may just be in my head from reading about knock sensors all day! So what should I do now? Buy a new knock sensor and replace it, purchase a Volt meter to test it (aren't these expensive?), or just see if the CEL comes on again? Sorry for the long post!

 

I would just keep checking if the knock sensor comes up on its own (no CEL, but the 0304 code). If it does, I would recommend replacing it. Not too hard to replace if you have small hands and tough skin.

 

I'll check again tomorrow. Do you know if the CEL flashes it means the engine is misfiring

 

I believe ONLY if it continues to flash while you are actually driving the car. I have'nt actually heard any cases of Max's having their CEL blink or flash under normal driving conditions. I know one time, when I tried to reset my computer one time, the CEL flashed a few times upon start up, but then it went away and never did it again. Maybe, the computer was "self-adjusting" ? This happened to me last year, and I never had any major problems because of it. I meant to ask a Nissan mechanic about this, but it always slipped my mind. Again, I would only start to worry only if the CEL flashes/blinks WHILE driving. Then, something is DEFINITELY going wrong with the car that needs attending to!

 

The CEL blinking is a major fault, misfiring could be one cause since that would cook your catalytic in a hurry. There's a bunch of "bad" codes that would make it blink while driving. Excessive lean mixtures too since you could melt holes in the pistons..... Excessive knock would also trip it(or a faulty sensor thinking it was knock) which would retard the timing to be on the safe side.

I'd just replace the knock sensor if I were you.

Fun stuff

-RMB

 

It only flashed that 1 time after I got the code and reset the ECU, it went away a second after I started the car, I didn't drive at all.

 

i would just check out the knock sensor and see what's up with it. do a few tests to see if all the terminals check out fine (tip: don't go pushing tips of voltmeters inside terminals, it can mess them up and you'll definitely need a new one). hopefully, it'll be a faulty knock sensor, becuz if your car is knocking.... yikes. btw, unless it flashes while driving down the road, don't worry much.