I had two check engine light codes..the first said Too Lean (bank 1) and the second said Fuel Trim Malfunction (bank 1) so I replaced my primary O2 sensor and the codes are not GONE!! but now I am throwing a PO420 code for the catalyst system....but what I want to know is...am I still running lean? I checked my plugs at idle and parked at around 3,000 rpm and they are a bit grayish and tan(a yellowish tan)...??? What I am wondering is am I still running lean? because my two lean codes are no longer there...

Thanks in advance!!

 

Could be your secondary 02 sensor too. Have you let the car warm up and driven it anywhere? You may still have a CEL if you haven't.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Lan &raquo;</TD></TR><TR><TD CLASS="quote">Could be your secondary 02 sensor too. Have you let the car warm up and driven it anywhere? You may still have a CEL if you haven't.</TD></TR></TABLE>
Good point^ is the car OBD2? but could be a bad cat.

 

Warm up the car good, then reset the ecu...then check for codes again.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by jdm_bones &raquo;</TD></TR><TR><TD CLASS="quote">Good point^ is the car OBD2? but could be a bad cat.</TD></TR></TABLE>

I think it is, look at his SN. I had to gut my cat because I couldn't see through the damn thing Then I had to wrie a 02 simulator to the secondary because I kept getting CEL's

 

Well, I reset the ECU right when I changed my primary O2...and that was on Friday..normally the lean code returns after a day or two of driving and I checked it yesterday and that's when I saw the PO420 code...I was under the impression the rear O2 doesn't have much to do with the air/fuel ratio as much as the primary...??? so why would it matter if the rear one is bad? But either way...my plugs are grayish..and they used to be brownish..I have an adjustable FPR but don't want to raise it because I don't want to risk running rich and messing up my O2 sensor, considering I just bought it..

 

You should check your secondary, it actually signals the A/F to the ECU after the car is warmed up. I understand why you wouldn't want to turn you FPR up, but it won't ruin a new 02 if you get your A/F's dialed in eventually on a dyno. Are you running Hondata, Crome, Neptune? Anyways, turn the FPR up, if you run too lean your motor could blow

 

see that's the thing..I only have an adjustable FPR...I don't have anything to tune with...so if I raise it...I might be giving it too much fuel pressure...I want to take it and get it dynoed..but I think with 20 or so dollars more I can just buy a rear O2 sensor from Denso..but is it possible for my car to still run lean and the codes don't come back? Because I figured since the codes aren't there than I should be fine. Let me know what you think!

Thanks!!

 

Oh yeah..one more thing..how would I check my rear O2 sensor myself?

 

I called the Acura dealer and talked to a tech...he said that the grayish plugs are normal...he sounded pretty confident...