Just got a high flow cat done and when I drive for a few minutes the CEL will turn on also I do notice it usually turns on asap when I'm on the freeway. I also smell carbon and my mpg is horrible... First thing I've done is switch the fuel filter and still have this problem. Any suggestions? Thanks.

 

Anyone? Ttt

 

Year?
Make?
Model?
Engine?
Transmission?
ECU/ECM?
Harness?
Any and all mods besides the high-flow cat?

Code 43 is set when the ECU/ECM can't make up its mind whether the oxygen sensor is responding incorrectly to ECU control, or the fuel pressure is incorrect.

 

how big is the pipe for the exhaust from the cat back?

Header?

is the O2 even pluged in?

 

96 gsr, 99 tranny, chipped p28 on gsr basemap. OBD1. Only mod is IM and 2.25 hi flo cat, everything is stock, headers and b pipe. Yes o2 is plugged... Ttt

 

Things to check.
Is the oxygen sensor good?
Could the exhaust manifold have a hairline crack?
Fuel Pressure regulator o-ring renew with silicon grease or replace.

 

code 43 is set when the pcm believes there is a fuel related issue. although many times it's not a fuel related issue, but rather only the ecm's interpretation of it.
first thing that needs to be accounted for is fuel pressure/flow.
install a fuel pressure gauge at the supply line after the filter. KOER, observe pressure. pinch the vacuum line off fuel pressure reg. pressure should rise approx. 8-10psi. if not, replace the reg. if good, with reg still pinched, snap the throttle 3 times to approx. 3k. pressure should not deviate more than 2 psi. if it does, there is a flow issue, ie, failing pump.
this is a great test for confirming FPR operation and flow

while the fuel supply is not the #1 cause of a code43, it must be disqualified.
try that out and see what you get and we can move further

 

I'm getting a new O2 sensor and headers just cause then I'll check with the fuel regulator... See what happens. Thanks guys!