I have a code 43.Can anyone give me a possible answer to what would need to be fixed in order the fix this. I have a 91 Ls with a b17 swap. Its been in my car for 3 years with zero problems. I think the problem started when my alternator went and it starting over charging my battery to 16 volts which meant the regulater on the alternator was bad, so I changed the alternator. PLease help
code 43 is fuel supply system … but i think its the O2 sensor
could be anything… from the fuel pump to an goofy injector. Mine threw a 43 awhile back after I had cleaned the engine… turns out it was just water that got into an injector clip… dried it out cleared the code no more issues.
what were the circumstances that led to it popping the code. Detailed info will help get ya a better answer as most codes on these cars are rather vague and only point to a system that has a point of failure.
as mentioned, code 43 can be set by any number of malfunctioning sensors/actuators. even an ignition problem can set it.
the best place to start whenever dealing with a fuel related issue on an efi system is the primary o2 sensor. to test the o2 accurately, you’ll have to use an oscilloscope. an oscillioscope uses an actual graph rather than numbers and is fast enough to read the o2 signal accurately, unlike a dvom. testing involves fogging in propane through the intake to test o2 range and snapping the throttle to test its response time.
you could check range with a dvom. but response time definitely needs to be scoped. to check the range, scale the dvom to read mV. back probe the o2 signal wire and get the vehicle to operating temp. fog in a shot of propane into the intake. the reading should jump to around 900mV. if it jumps to anything less than 900, it’s a fail