I have a 96 SE 5sp with 170K miles. Until recently, the car has been relatively trouble-free. I have had repeated problems lately with the engine light. Here is the recent history. In November, the light came on and the codes were O2 and knock sensor. The mechanic said there was corrosion around the knock sensor and cleaned it. The codes were cleared. Last month, the light came on again and the codes were O2 (P0136) and knock (P0325) sensors and evap vent (P0446). The front O2 sensor was replaced. The codes were cleared. Last week, light came on again and the code was the knock sensor (P0325). The mechanic replaced a wiring harness and a cracked knock sensor. The codes were cleared. The next day, the light came on again. This brings me to today, $1,000 later and several visits to the mechanic (Due to circumstances largely beyond my control, the work was performed by 3 different shops).

My question for any expert is if there is some systemic problem for which my recent repairs have only been addressing symptoms. For example, is it possible that the cat converter is defective?

 

The o2 sensor was the culprit here. Thats the only thing that should have been replaced. The other codes (KS) are ghost codes caused by the failed o2 sensor. The evap vent valve may have gone bad, or your gas cap may be lose.

You could have checked the codes yourself - cost $0

Then came to the orgy for help.

You could have had the o2 sensor replaced by a mechanic or done it yourself - cost ~$200

The other 800 would have made for a nice vacation someplace.

 

Are you saying that the light coming on now for the fourth time means nothing (as well as the third time, since round 2 was when the O2 sensor was replaced)? Also, if the knock sensor was replaced in round 3, what makes you think that a cracked knock sensor wouldn't have been the problem for an engine light?

Thanks,
Brian

 

Check the codes yourself. Look at the thread at the top of this page entitled Help my check engine light is on. Then post what the codes are and we'll help you out.

Knock Sensor....
In your original post, you mentioned that a mechanic "cleaned" some corrosion around your KS. Doesn't sound right... Next round it's suddenly cracked? I don't think so.... The second mechanic just read the code and replaced what it indicated.

The KS code is set quite often from something else failing. In your first case, it was the o2 sensor. You still may have something wrong being the light is on, so read the sticky thread and pull the codes yourself and post them back here.

Were always here to help you out!

Tom

 

Just because you get a code for a knock sensor, that does not neccasarily mean that your knock sensor is bad. I wonder if it cracked when the guy was cleaning the corosion off of it. Good luck in the future. If you don't want to use the screw in the computer to read codes, and your car runs, take it to Autozone, they'll pull the codes for free.

 

This sounds odd.

Check out my website, it has a great pic of an old knock sensor
and where it's located...

knock sensor pic

as for the what's above...there is more than one O2 sensor, and these
are notoriously bad...

hope this helps!
FLO_BOY

 

I got a right O2 sensor (0503) and a closed loop control (0307). Should I:

1. Wait for the light to return.
2. Replace the right O2 sensor. The sensor will cost about what a shop would charge just to evaluate the problem.
3. Take it to a shop for their diagnosis.

Thanks,
Brian

 

Reset the ECU.

If the same code comes back for the o2 sensor, then replace it.

Don't pay to have anybody diagnos anything. Do it yourself then tell your mechanic what you want done. You can even bring him the code YOU pulled out so he knows which o2 sensor it is.

Good luck!