problem with O2 codes on 2004 Civic HX

[dr_dx]

Hi!

Just looking for some help with getting the O2 Xgauge codes to work on a 2004 Civic HX. It has the D17A6 ULEV motor with 3 O2 sensors. I think it uses ISO mode (at least when I set it to Auto and it reconnects, it shows ISO). I have programmed the ISO O2 B1S1, B1S2, and B2S1 xgauges. I get no response from B1S1 or B2S1. For B1S2, I will get a number that fluctuates from 35~85 for the first 15 minutes of driving and then it goes to 0. After that, it will go to 1 momentarily but usually just stays at 0. I get not CEL or anything and my mpg doesn't seem to be affected.

Any thoughts?

[CarlD]

Originally Posted by dr_dx

Hi!

Just looking for some help with getting the O2 Xgauge codes to work on a 2004 Civic HX. It has the D17A6 ULEV motor with 3 O2 sensors. I think it uses ISO mode (at least when I set it to Auto and it reconnects, it shows ISO). I have programmed the ISO O2 B1S1, B1S2, and B2S1 xgauges. I get no response from B1S1 or B2S1. For B1S2, I will get a number that fluctuates from 35~85 for the first 15 minutes of driving and then it goes to 0. After that, it will go to 1 momentarily but usually just stays at 0. I get not CEL or anything and my mpg doesn't seem to be affected.

Any thoughts?

Probably the xgauges that don't display anything are due to the PIDs not being supported by your vehicle. You can get a supported PIDs mask by sending the mode $01 PID of $00 and then bitwise decoding it. For an ISO, you would go to CMNDS and enter 686AF10100 and hit send.

For the O2 xgauges, I think they are incorrect on the LL website. If you are looking for the O2 sensor voltage, the B1S2 xgauge would be:

TXD: 686AF10115
RXF: 044145150000
RXD: 2808
MTH: 000100020000
NAM: O12

Which will give you a fluctuating reading between ~.1 and ~ 1 volts when warm and closed loop with a narrow band sensor. In lean burn, it will stay near 0.

You could leave the RFX the same as on the LL website but change the MTH to be 000500010000 to get a voltage reading with units of millivolts.

[dr_dx]

"For an ISO, you would go to CMNDS and enter 686AF10100 and hit send."

I did that and the result was:

486B114100BE3EAC11BE

I also tried changing the 0>4 in the RXF string but it didn't change anything. ISO O11, O21, and O22 have no reading. ISO O12 works the same as above. BTW, the leanburn xguage appears to be the same as the ISO O12.

[CarlD]

Originally Posted by dr_dx

"For an ISO, you would go to CMNDS and enter 686AF10100 and hit send."

I did that and the result was:

486B114100BE3EAC11BE

I also tried changing the 0>4 in the RXF string but it didn't change anything. ISO O11, O21, and O22 have no reading. ISO O12 works the same as above. BTW, the leanburn xguage appears to be the same as the ISO O12.

The supported PIDs are decoded as follows from the B E 3 E A C 1 1 data:
B E 3 E A C 1 1
1011 1110 0011 1110 1010 1100 0001 0001
^ ..........................................................^
$01.......................................................$20

so PIDs 01,03,04,05,06,07,0B,0C,0D,0E,0F,11,13,15,16,1C,20 are supported. The fact that PID $20 is supported means more PIDs can be listed by sending:

686AF10120 which will give the supported PIDs mask for PIDS $21-40.

Changing the 0 to 4 in the RXF had to have made a difference. No way numbers >1.27 could be displayed with the 4 in there.

[Right Lane Cruiser]

I know I'm a bit late to this, but I'm still confused about how I'm supposed to know what PID is for what function?

[CarlD]

Originally Posted by Right Lane Cruiser

I know I'm a bit late to this, but I'm still confused about how I'm supposed to know what PID is for what function?

http://en.wikipedia.org/wiki/OBD-II_PIDs

should help with that.

[Right Lane Cruiser]

Thanks, Carl!

[dr_dx]

Originally Posted by CarlD

The supported PIDs are decoded as follows from the B E 3 E A C 1 1 data:
B E 3 E A C 1 1
1011 1110 0011 1110 1010 1100 0001 0001
^ ..........................................................^
$01.......................................................$20

so PIDs 01,03,04,05,06,07,0B,0C,0D,0E,0F,11,13,15,16,1C,20 are supported. The fact that PID $20 is supported means more PIDs can be listed by sending:

686AF10120 which will give the supported PIDs mask for PIDS $21-40.

Changing the 0 to 4 in the RXF had to have made a difference. No way numbers >1.27 could be displayed with the 4 in there.

CarlD,

You da MAN! You are right the LB xguage has a max reading of 1.27. So what is the LB threshold? Any value below 1? During my drive today, I saw values from 0.00~0.87 With the other Mth setting you would get a 0 value or something else. Supposedly, a 0 meant you were in LB and any other value meant that you weren't.

Also the result for 686AF10120 = 486B11412000001000035

Thanks for all of your help!

[CarlD]

Originally Posted by dr_dx

CarlD,

You da MAN! You are right the LB xguage has a max reading of 1.27. So what is the LB threshold? Any value below 1? During my drive today, I saw values from 0.00~0.87 With the other Mth setting you would get a 0 value or something else. Supposedly, a 0 meant you were in LB and any other value meant that you weren't.

Also the result for 686AF10120 = 486B11412000001000035

Thanks for all of your help!

Well, it looks like you have a lambda sensor PID ($34) supported , so that would be the best way to determine LB. If lambda >1.0, you are lean; if lambda<1.0, rich.

This xguage will just display the lambda value:

TXD: 686AF10134
RXF: 044145340000
RXD: 2810
MTH: 001920000000
NAM: LAM

You could try an actual LB xgauge by doing the following:

TXD: 686AF10134
RXF: 044125340000
RXD: 2810
MTH: 000180020000
NAM: LBn

You might have to play around with the highlighted 2 in MTH to really determine pure LB vs. switching between rich/lean for the catalyst. If you code up the lambda xgauge and watch what it displays in LB, you can the adjust the MTH for the LBn xgauge. The MTH for the LBn xgauge may end up being 000190000000 or something like that to avoid displaying "ON" when not actually in LB.

[dr_dx]

Cool! I coded them both up and am working on the "2". Is $34 the only supported PID in the $21-40 range?

Thanks,
Dr Dx