matrix11229

I bought this car 2 months ago with check engine light on. I had it computer diagnosed by mechanic and I got codes PO150 (O2 sensor) and PO325(Knock sensor) and the system was reset.

Then I replaced both of my front O2 sensors and Knock sensor (from eBay), and I felt improvement in performance , gas mileage and the car is not shaking any more when it stands with shifter on D (now there is only minor vibration).

Since the reset my MIL is off and the car drives fine.

So today I decided to check for ghost codes by turning the ECU selector and voila I got the following codes:

0304 -Knock sensor again !

0705- Evap Control System

0903- Evap Canister Vent Control Valve


So my questions are:

1. What's the problem with Knock sensor ? I didn't have a torque wrench so may be I over tighten the bolt ? The harness looks fine . Also the seller of the knock sensor has 100% positive feedback on ebay and he sells tens of those sensors every week so I trust him and the sensor is brand new.

Should I play with the torque on the sensor bolt ? And how can I check that it worked (i mean the ghost code will not show up again) ?

2. I checked the stickies, they say that 0705 points to so many things you don't know what to check, so it is often combined with another code which is more specific and therefore more helpful.
Thus, 0903 probably is the problem. The stickies say that since this valve it is used only for self-diagnosis your engine will run perfectly anyway. A loose connector could be a problem.

Why the last two codes didn't show up on my mechanic's computer 2 months ago ?

Did anyone have those codes ?
What should I do now ?

95jr6708

I would start by resetting the computer again...I replaced the knock sensor as well and it threw the code the next day for some reason i reset it again and it has never come on since. It could be the torque i guess, given that the tighter it is the more sensitive it is and the looser it is the less sensitive it is..i did not have a torque wrench either as the one i had was too large to fit. so i just put it on with decent common sense, but i believe the OEM specification is somewhere around 20-30lbs of torque. As far as the evap codes, if you are worried that much, i would look at ALL of the hoses for cracks or visible damage...leaks etc. And as far as why it didn't show up 2 months ago, well, things can happen in 2 months. Good luck.

matrix11229

Thanks for your help James !

Did you have a CEL on or a ghost code on the next day ?
You reset it by turning the ecu selector or using a computer ?
Did you feel any improvement in performance/mileage and less vibration after the replacement ?

95jr6708

I reset it by turning the ecu screw. I replaced mine because it threw a CEL. so i pulled it out and sure enough it was cracked in 3 places. It was hard to tell performance wise, because i had no idea it was bad, but gas mileage went threw the roof it seemed like. If i may suggest if you are having problems with performance i cleaned my throttle body and iac valve and wow! Idles much smoother and pick up is much more defined if you know what i mean. Only thing i have done where i could really tell a difference and not just have the placebo effect.

oh and when my CEL came on, my car started to idle real low so maybe that is what you are talking about...it had no power, no idle and shook like a motha fuc*a. so hopefully you'll get that taken care of...good luck.

matrix11229

Thanks !!!

MaximaSpd85

iTrader: (14)

i had the 0705 and the 0903 for a longggg time until i finally got it figured out. the canister is the black box underneath your car near your left rear tire. try removing the valve thats on it and spraying something in it like wd40, b/c if i recall correctly the problem with the valve is that sometimes it gets stuck or something?? anyway, mine didnt come off, the bolts kept spinning and spinning, and this is b/c on the inside of the canister the back of the bolt is somehow snapped or something and it just spins. not sure, but something of that nature. so i didnt do anything until i found one at a junkyard, which i took a chance on, and i put that one on and the codes went away.

cliff notes: replace the canister!! lol

matrix11229

What exactly you bought at a junkyard ? The Valve ? How much you payed ?

From which side of the canister the valve bolts are located ?

How a defective valve affects the car ? I mean this valve does something... besides throwing codes lol


Thanks for your help !!!

Mxrider52

iTrader: (8)

There probably nothing wrong with your knock sensor. The first time it was on was because you had bad O2 sensors. You should have just replaced the O2 sensors and reset the ECU. The KS should have went off more then likely.

Just like now the KS isnt what is bad it getting a bad reading due to your other codes which is throwing the KS code.

You should never replace the knock sensor if you have other codes. Always fix the other problems reset the ECU and if the KS code comes back then you have a bad KS.

Bservice

To test for the knock sensor check the sub connector harness. Its a connector if you follow the wires from the actual knock sensor. The specifics are in the stickies I think its supposed to be like 450-550 Mohms. The computer ussually throws the code if the resistance isnt to spec or there is a circuit problem to the KS