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While trying to figure out my fuel trims, I noticed the cat temps.
When I saw the high temps on the 15765-4 protocol, I jumped over to the Honda side and get a different number.
1000* cat temp just about flipped me out, but the 547* is more believable.


Both temperature readings taken close to the same time during live data stream.
One on the OBD2 side, other on the Honda side.

On OBD2 Side, protocol ISO 15765-4 CAN (29 bit)
Catalyst Temp Bank 1 sensor 1 .. 1075*F
Catalyst Temp Bank 2 sensor 1 .. 1075*F

On Honda side of scanner, it just shows protocol '(CAN)'
Catalyst Temp Bank 1 sensor 1 .. 547*F
Catalyst Temp Bank 2 sensor 1 .. 547*F

The same for fuel trims.

OBD2 15765-4
Short 1 (9.4) + long 1 (10.2) = 19.6
Short 2 (7.8) + long 2 (7.8) = 15.6

Honda Side.
Short Term Fuel Trim (lambda) 1.000
Short Term Fuel Trim Bank 1 ... 1.009
Short Term Fuel Trim Bank 2 ... 1.009

The OBD2 side shows I have a lean condition while Honda side shows I'm good
The cat temp difference is still bugging me.
Truck is a 09' with 40k miles, no codes showing, runs great and average 18.5 - 19.5 in mixed driving.
What I'm I failing to understand here?

Anyone have a clue or would this be better suited on one of the VTEC/J series forums.
Well, 1075F = 579C which isn't too far off. Maybe one is labeled wrong. It would make sense that if the Honda side was in Celsius. I notised they used KPa vs PSI, so the "international" units seem to be in play.
 

· Registered
Joined
·
5,700 Posts
While trying to figure out my fuel trims, I noticed the cat temps.
When I saw the high temps on the 15765-4 protocol, I jumped over to the Honda side and get a different number.
1000* cat temp just about flipped me out, but the 547* is more believable.


Both temperature readings taken close to the same time during live data stream.
One on the OBD2 side, other on the Honda side.

On OBD2 Side, protocol ISO 15765-4 CAN (29 bit)
Catalyst Temp Bank 1 sensor 1 .. 1075*F
Catalyst Temp Bank 2 sensor 1 .. 1075*F

On Honda side of scanner, it just shows protocol '(CAN)'
Catalyst Temp Bank 1 sensor 1 .. 547*F
Catalyst Temp Bank 2 sensor 1 .. 547*F

The same for fuel trims.

OBD2 15765-4
Short 1 (9.4) + long 1 (10.2) = 19.6
Short 2 (7.8) + long 2 (7.8) = 15.6

Honda Side.
Short Term Fuel Trim (lambda) 1.000
Short Term Fuel Trim Bank 1 ... 1.009
Short Term Fuel Trim Bank 2 ... 1.009

The OBD2 side shows I have a lean condition while Honda side shows I'm good
The cat temp difference is still bugging me.
Truck is a 09' with 40k miles, no codes showing, runs great and average 18.5 - 19.5 in mixed driving.
What I'm I failing to understand here?

Anyone have a clue or would this be better suited on one of the VTEC/J series forums.
Well, 1075F = 579C which isn't too far off. Maybe one is labeled wrong. It would make sense that if the Honda side was in Celsius. I noticed they used KPa vs PSI, so the "international" units seem to be in play. I also remember that Cats are VERY hot (more than mufflers).... I just don't recall how hot.
 
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