engine misfires. get trouble code 172 EGO not switching lean exhaust bank 1. could an oxygen sensor be causing this misfire?

 

Possible, but not likely..You could have a really dirty MAF sensor, or a nasty vacuum leak, or your EGR valve, gasket, and hoses to it have given up for dead.. Need to clean your MAF with SPRAY CLEANER ONLY- do NOT touch the element with anything but the spray..Look around for vacuum leaks, such as old cracked vacuum hoses, lines, and "tee" fittings.. Try spraying carb cleaner around gaskets like the throttle body(not in it), and other vacuum sources..need to pressure test your EGR valve, or try this: with the engine idling, up to operating temp, try to push in the rubber valve boot inside the housing, and if it doesn't make the engine stumble or quit, or it keeps running the way it is, then the EGR is no good..If the engine stumbles, then it should be OK..spray some carb cleaner there too, as the gasket could be history..I don't know mileage or year of your truck, and WELCOME to FTE, and in the future it helps us help you if you include this info, as in year, engine, model, mileage, and the like, as in how long have you had this problem, and how the vehicle, or engine is acting..There are a lot of good people on this forum who can help, just need the info.. Again, WELCOME!!!!

 

Sorry. It's a 1994 mazda B4000 4.0 v6, same as ford. Used a snap-on scan tool to retrieve trouble code 172. No exhaust leaks or water leaks. Recently changed the cam position sensor but only code I get is 172 EGO not switching lean exhaust bank 1. Hope this clarifies my problem

 

PLEASE, go back and read my previous post, as these are the problems you WILL encounter when you have a code 172-I didn't say anything about exhaust or water leaks, as I said VACUUM leaks, as in INTAKE manifold leaks, and all VACUUM hoses, and your EGR valve malfunctioning...

 

Although and exhaust leak can cause you code, such a leak would be painfully obvious. But intake leaks are subtle. You should replace the O2 sensor due to your mileage and age ( I know you didn't mention what your mileage is, but its almost certainly more than 80,000 miles, the recommended interval for O2 sensors), but I suspect an intake leak is probably your issue.