Hey guys, heres the story. I was driving around and popped a check engine light, got the codes read. They came up as: P0171 and P0170 (system to lean bank 1 and fuel trim malfunction bank 1). So my question is, could this be related to an o2 sensor going bad? Like would a bad o2 sensor make these CELs pop? (Bank one is where the o2 sensor is located in the header right?)

If not, what all should I start looking at as a cause?

Anyway, thanks for your help, any and all is welcome!!

 

I would start by measuring the fuel pressure:

 

That looks like its out of some service manual. Is that something I can acquire?

 

I PM'd you.

 

im having the same code too...it said check vacuum if theres a leak too..
but i have a 00 si with an ITR IM. and one of the hose i didnt need but i didnt plug it right properly..so im gonna check that first.

 

So, this is a bit old, but I hadn't had time to diagnose and work on my CEL. I went and got it read today at AutoZone and I had 3 codes: P0135, P0170, P0171.

Is it possible that P0135 (bad o2 sensor) could have caused the other two to start with??

 

Yes, fixing P0135 may fix all three codes.

 

Hm, ok that will be my first priority. Now, the P0135 code didn't happen right away, its been a few months like this before I even pulled that code. Is that going to make a difference?

 

It shouldn't matter.

 

Yea I have that manual, and I noticed that a bad o2 sensor is a common cause between the two, but I just didn't know if it would matter that it came later.

Also, on page 11-157 of that manual it shows how to test if the o2 sensor is bad, on the second step we're measuring for continuity between the battery and the connector. What does it mean by continuity. IE should it read a certain number of Ohms?

 

Continuity means a reading of very little or no resistance (= ~0 Ohms).