17 mpg...wtf, this ain't no V8

[redchile]

My car is a stock '95 240sx and it has been killing a lot of gas lately. The check engine light came on and reads codes: P0402=excessive flow in exhaust gas recirculation system P0325=knock sensorHow is this affecting my mpg? I did purchase the sensor and seems like a ***** to install but is this going to fix the problem or should I check the timing. Last week I changed the O2 sensor, and no change.Also, should the harness connecting to the knock sensor have 1 or 2 wires going into it? I see only one and don't know if one broke off or it only has one. I would appreciate all the info guys. Thanks

[vocationalzero]

My car is a stock '95 240sx and it has been killing a lot of gas lately. The check engine light came on and reads codes: P0402=excessive flow in exhaust gas recirculation system P0325=knock sensorHow is this affecting my mpg? I did purchase the sensor and seems like a ***** to install but is this going to fix the problem or should I check the timing. Last week I changed the O2 sensor, and no change.Also, should the harness connecting to the knock sensor have 1 or 2 wires going into it? I see only one and don't know if one broke off or it only has one. I would appreciate all the info guys. Thanks

P0402 is the EGR valve, it is saying it's stuck open and you need to pull it off and either a) clean with carb cleaner and a wire brush; or b) replace itAnd the knock sensor code is thrown to help prevent you from getting a knockin sound.

[simmode1]

Dude, this is so helpful! My 96 Zenki is doing the same thing and throwing the same codes!

This problem don't seem so bad!

[480sx]

From the sound of the code you have an EGR system problem. You might need a new EGR valve, or one of the solenoids that control it. Since your in Ca, your fked because you have to get that to work to pass emissions.

Also, your knock sensor can definitely give you bad gas mileage. It will retard the ignition so you will need to give it more gas for the same engine load. First, replace that for sure, your MPG will go up. Make sure to get an OEM replacement.

Also install that new O2 sensor. They also will cause you to get poor gas mileage. Also, you need it to be an OEM sensor, i have never been able to get an aftermarket sensor that will clear the o2 system codes. Your lucky because yours is a 95 and your OEM sensors are cheap. Unless your some funky Ca version that already had OBD2 stuff on it...

[redchile]

No kiddin'...I have to smog this car in April. Now, by changing the knock sensor (f*ckin pricey), will the computer rediagnose itself and set everything back to normal specs or will I have to mess with the timing?

[480sx]

When you install it the ECU will do the adjustments.

[nzmoman]

P0402 is the EGR valve, it is saying it's stuck open and you need to pull it off and either a) clean with carb cleaner and a wire brush; or b) replace itAnd the knock sensor code is thrown to help prevent you from getting a knockin sound.

I've never had to do it, but I have heard knock sensors are a pain so pray you dont have to replace that.

[LOVERboy]

i have the same problem but my kouki doesnt eat 17 mpg tho. it came up everytime i rev past redline and hold it lil longer then two second. just clear it first and see what happen.( thats wat i did)

[redchile]

I cleared the codes last week and they came on again last night. I will clean the EGR valve and see what happens then.

[redchile]

Just changed the knock sensor (not as hard as I thought), but I could not get the EGR valve off...how the hell am I suppose to take that POS off?

[kaktus]

Just changed the knock sensor (not as hard as I thought), but I could not get the EGR valve off...how the hell am I suppose to take that POS off?

did you use the write-up from this site to change the knock sensor? that sh1.t is invisible under the intake manifold lol

[redchile]

Yeah I read the articles for the knock sensor, but it really wasn't that hard. Removal was easy once I moved a few things. Instead of using a wire to line it up I just held the sensor with the harness from the top of manifold and held the screw to socket with tape and then ran the wire back out towards the front. It wasnt bad at all...now, the EGR valve was the one that did defeat me. I couldnt take that garbage out, too tight to move anything back there. Any ideas?