Hello I've got a Mazda 3 with a 1.6 litre petrol engine. I foolishly failed to check the oil level and the engine warning light came on. Oil has subsequently been added and I've done a few thousand miles in it since with no noticeable difference to the car. However I can't turn the engine warning light off. When I plug a diagnostic tool in it reports a P0328 Knock Sensor problem. Should I change the sensor? Find whats causing the sensor to get upset? Or just ignore it since its not causing any problems? I have very limited understanding of cars (see line 3 above).
I'd leave it alone. If the car is running good why bother with the light? I put a piece of tape over a sensor light so it stopped bothering me.
Just out of curiosity, did you try disconnecting the battery overnight to reset the computer? I always try that and it work half the time. Disclaimer/Disclosure: Not a mechanic. I just play one on TV.
I'd recommend joining a Mazda forum and asking the question there. They'll likely have better advice from people who have seen this problem before. In general though, computers in cars are getting better and better. Error codes used to be very vague clues to what the real problem with your car may be. Nowadays they might just tell you exactly what the problem is and you may just need a new sensor. Driving around with a malfunctioning knock sensor may cause your timing to be retarded (firing late). That is to avoid detonation which will destroy your engine. It'll also give you terrible gas mileage, probably cause you to fail an emissions check (if you have to do those), make the engine perform poorly, and maybe cause some other problems. But you're not very likely to find a Mazda 3 expert on a shaving forum so I'd go looking for a forum that specializes at least in Mazdas or take the car to a dealer.
Removing the battery usually clears the ram of the current condition, which will be re-checked when you start up the car next time. If that doesn't fix the issue, then I strongly recommend replacing it for the reasons stated by @feeltheburn . The sensor is there for a reason and should be replaced.
You don't have to wait overnight. Just pull the ground on the battery and hold down the brake pedal for 30 seconds or so. Then re-attach the ground lead.
This explains everything you need to know about that engine code: http://engine-codes.com/p0328_mazda.html
Or you can bury a small piece of the upholstery in a cemetery at midnight with the proper incantations.
The above link was useful. It suggested my engine was not about to die. Just need to change the sensor. Thank you all for responding. I've have since bought a diagnostic tool. Hasn't arrived yet. Going to keep it in my VW, but that's another story.
