jdb12887

I just bought a 96 maxima very cheap. It has a few minor things I need to fix. I have a small oil leak near the center of the car, what should I check first. I ran codes for check engine light and it needs a knock sensor and egr valve? Are these things I necessarily need to replace for the life of the car? Also what are some other suggestions on other things I should replace with the car having that high mileage? New alternator, water pump, brakes and rotors have already been put on. Any and all help is appreciated. Thanks!!

BenL

Try cleaning the EGR tube[s] and valve first if it said EGR flow insufficient (there's a cleaning guide in the stickies), the passages love to collect carbon and can cause the valve to stick as well.
As for the knock sensor, I would only really worry about it if it's a code entirely by itself... a lot of the time it'll come up if there's another code set in the ECM and never be a problem.

njmaxseltd

iTrader: (19)

If the EGR code is for flow, not for the device itself, then clean the EGR tube and clear the code. If the code points to the valve, troubleshoot the system or replace the valve and clear the code.

If the knock sensor code continues to come back with no other code along with it, replace that sensor too.

A detailed inspection of the vehicle will show you any further times that need attention.

matts95max

iTrader: (11)

The oil leak is in the center of the car? Im not sure what could be leaking oil there as a section of your exhaust or catalytic converter is in the middle of you car.

If you meant the center of your engine bay it could be the rear main seal if its the upper part or maybe a rear valve cover if its in the rear of the engine bay, still centered.

If its a really small leak, I would wait until it gets worse before doing anything.

dwapenyi

iTrader: (3)

You can leave the knock sensor and the car will run forever. Because the KS code is on, the engine computer is automatically running a less aggressive fuel mapping, meaning less power and fuel economy if you were using 93 octane. If you run 87 octane, just leave the KS alone then.

As for the EGR, the car will probably run forever too with that code, or codes. The EGR is that pipe that circulates hot exhaust gas for the exhaust manifold back into the intake manifold. The EGR system helps with emissions by reducing NOx. The biggest thing to worry about from that is a failed emissions inspection. Other than that, the car will run fine, well, with more NOx in your exhaust.


If it was me, I would do both.
1. I want maximum power from the 93 octane I put in the tank, so the KS has got to be good.

2. I want the engine to run as efficiently and emission friendly as possible, too.

By the way, the reason your check engine light is on is because of the EGR code. If it was the KS code only, the CEL would not light up. In other words, the Nissan engineers knew full well that a KS code is an issue, but not an out and out problem.