Hey everyone,

I've been pulling 3 codes from my 2001 GLE:

P1440 - Evap
P0138 - O2 Sensor ( Bank 1, Sensor 2 )
P0325 - Knock Sensor

I've been driving the car for a few weeks now and I've been clearing the codes to see which ones come back. The EVAP one is very persistent (often showing up twice) and the knock sensor one seems to come back as well, but the O2 one is intermittent.

Now I've done a few searches and I know how to handle the EVAP one, however a lot of the information I find on the knock sensor code makes it sound like the knock sensor doesn't actually throw a code. Then there's other threads that talk about replacing the knock sensor. Whats the bottom line here? Given that the code has come back 4 times now after clearing the codes, is it safe to say I need to replace the knock sensor? I just don't want to tear off the UIM and LIM for nothing.

Also, the O2 sensor code has only come up twice since I got the car. Before I order a new one from amazon is it possible the knock sensor is causing the o2 code? My theory is that if the knock sensor is bad it retards the timing, and since I'm running 91 octane perhaps the exhaust is rich causing the O2 sensor code? I'm new this stuff so my theory may not make sense

 

Vacuum leak.

 

Vacuum leak would cause the knock sensor code as well? That would be awesome if I could kill 3 birds with one stone.

 

vacuum leak will cause lean condition, could be intermittent enough to cause a knock.

Or you could have a bad knock sensor and this stuff. Either way you need to do a vacuum check, if it's leaking, fix it, clear codes and see what happens. Cheap & easy.

 

P1448- clean the valve on the charcoal canister...maybe stuck open or closed!
inspect knock sensor and do look for a vacuum leak...