these codes showed up recently when i connected the ecu due to a check engine light. the tach doesnt work except for the battery, & engine temp gauges. the Temp. needle leans far to the H side after long idle or stop and go traffic. on the highway it starts leaning back to the middle where it belongs.
ive heard this could be due to clogged cat's but changed a cat to a universal and still the have the same issue p0432

p0304 says cyl 4 misfire detected i assume this is just a calling for a change of spark plugs which will be taken care of, if anyone knows better about this code please enlighten

p0501 says speed sensor A range/ performance, i have no idea what this may be just speculate it could be because the faulty tach.

its a 1998 Audi A4 2.8, has about 140, 000 i just got it about a week ago and am tryin to get it all fixed up before inspection. all ideas welcome. thanks

 

First step is always to clear the codes and see what comes back. Transient codes can happen if the system farts, so this separates the real faults from one-time glitches.

If you swapped the cat and still have 0432, it's likely the secondary O2 sensor after that cat. The misfire could happen from a bit of bad gas or bogging the engine or not cranking long enough for it to catch. Speed sensor A is one of the engine speed sensors or the vehicle speed sensor. Any of those is very rare. Clear them all, drive, and see what comes back. Then you can troubleshoot without wasting your time potentially chasing ghosts.