New problem: Yesterday the Check Engine light came on solidly (I had been getting an intermittent Code 13, but I wasn't worried about that) and now I'm getting a Code 43. I cleared the codes twice and I get them again. Code 43 seems to mean that the ECM is detecting detonation and so it is retarding the spark timing to prevent engine knock. Why would there be detonation? I'm using 87 octane gas just like I always have and just like what the manual calls for. Anyway, the engine seems to run smoothly, but I'm missing a little bit of power and my economy has dropped from 22 to 18 MPG. The exhaust is blowing with excessive force and feels hotter than usual.

Short of going to a dealer and paying $$$$$$$$$$$$$$$$$$$$$$$, is there anything I can do at home without any fancy tools to check if maybe there's a false detection of detonation?

Maybe you have crud deposits in your motor that are stepping up the compression and causing knock? Try some kind of carbon deposit remover like seafoam through the throttle body.

2002 Cavalier 2200 5spd

Umm like that code 43 is for the spark knock sensor either 1 the spark knock sensor is going bad,or check the wiring for the spark knock sensor for a poor connection and ensure ur plug wires are not shot,or rubbing against each other,but 2 ultimatley ur spark knock sensor is bad creating the code!And how old is ur O2 sensor if it is way old or lots of mileage replace it!The reason ur car is running rich and poor mpg is prolly the O2 sensor go for that first and if it continues with the code 43 do the knock sensor and the should correct the issue.I am a first gen junky and know quite abit about them even tho I do have 4 bangr symptoms are the same.It's a simple fix and this should correct it.

As a matter of fat, it needs new plug wires.

It looks like the plug wire to Cylinder #1 has a worn spot in it, apparently from getting too close to the exhaust. I could understand how that could cause a miss or sputter, but could it cause a knock?

Well with a bad wire a poor wire could cause the knock being ur running on 3 cylders and not four.After replacing ur wires and plugs a good idea this should resolve the issue.But the O2 sensor could be a issue if after the replacement of the above does not change and u get the code for the O2 sensor replace it.The knock would be a NORMAL sign when a spark plug wire is faulty so do not worry!OK

So, I've replaced the plug wires and cleared the codes. I now have all my power back. The idle isn't exactly what it should be: It's down around 750 and not the smoothest, but there is no loss of power whatsoever when driving. The Check Engine light comes on once the car reaches its idle speed (of about 750), but no codes seem to be set.

Nope, I just thought I was good. Problem apparently wasn't the spark plug wires. After a while of driving and everything going fine, now I'm back with the same not-so-great idle, loss of power, and codes 13 and 43 set. Where do I go from here?

Ok you should Definitely replace the O2 sensor,if after replacing it the symptoms improve but,do not 100% fix it u will need to buy a a knock sensor for it.What happens is the O2 sensor going bad causes the car to run rich inturn making the timing retard to compensate for the lean/rich mixture.The knock sensor going creates a similar issue but retards the timing and affects the cars idle and basic performance overall.Check ur local advance auto or auto zone for the O2 should be around 20 bux or so guessing the knock sensor if it bcomes necess to replace I do not know a cost right off to even guess at.Start by replacing the oxygen sensor and see if after doing so and clearing the codes if the 43 comes back replace the knock sensor which I do not know exactly where its located but is defin located on the block and set the 43 code and cause sluggish perf,and retard the timing,they technically call the part the ESC knock sensor for ur info.

By the way, a knock sensor is $39.

Okay, so you say I should certainly replace the oxygen sensor. No problem. That'll run me $19.99 and tax. I'll see if I can do that tomorrow and I'll let you know what happens.

Ok I just suggested the cheaper of the two being the O2 sensor can cause some of the issues.But ultimatly if the 43 continues which in my opinion will bc of age u will have to end up buying that esc knock sensor to truly get the problem resolved.Hope the cheaper route works and fixes it,but doubt the knock sensor is doing the job after so many yrs of service.Good luck.

I have just replaced the oxygen sensor and tested the car again. The idle seems a little bit smoother, but I still get the Code 43. I don't, however, seem to be getting Code 13.

New knock sensor looks to be in ur future.That is what I would do and whala u should be back up par.OK

Now I have a new oxygen sensor and a new knock sensor installed on the car. I'm still having the same problem. Just seconds after I start the car, the Check Engine light comes on and the car goes into a low (about 700-800 RPM) unsteady idle. I check the codes, and Code 43 has been stored, as though the engine really is knocking.

I think I have narrowed the problem to a faulty wire. I get the exact same results with the knock sensor wire completely disconnected. Where do I go from here?

Let me think on it I am really tired tonight and just zippn thru here.I will c what my knowledge can do for me friday and help to resolve the issue.I will try and post something this wkend or tommorrow.Ok, and by the way just disconnecting the plug to the knock would cause the code bc the sender wire for that knock sensor is like a ground and would immeditiately cause the code to show regardless,bc its not hooked up.

You could be right there. According to what I read, the ECM supplies the ESC (CKT 496, dark blue .8) with 5 volts. Under normal conditions, the ESC drops this voltage to around 2.5 volts, give or take a few tenths. If this voltage drops below 1.5 volts (which would happen if the wire is broken or disconnected somewhere) or doesn't drop below 3.5 volts (which would happen if the wire is grounded somewhere), Code 43 will set. It looks like the only way I would know for sure (outside of running a whole new wire from F9 on the ECM to the ESC) is to use a high-impedence (at least 10 megohm) voltmeter on CKT 496.

Well with a fresh mind I put to thought ur issue.Obviously the cars idle is low and after replacing the knock and O2 the code 43 reset again.This makes me believe that the wiring for the knock sensor is faulty meaning a break or poor continuity for that sensor.I would do a continuity check on the with a audible multimeter to see if the wiring is making a solid connection.IF not I would either trace the wiring for crimps or even it being loose at the ecm bc being the ecm is not registering the signal would make the code set bc of no reading there fore causing the code to set even with the new part.Start with that see if u can pinpoint the issue which to me sounds clearly like it is isolated to the knock sensor only and not anything else that could cause the code or related problems like the egr valve,map sensor,mat sensor or even the iac (idle air control) which all normally set codes and can cause the idle issue or worse the timing being off bc of wear etc.Try the above and I will do my best to assist u knowlegde wise,but believe its in the harness for the knock sensor.