2000 Mercury Cougar P0172 Code: Over-Fueling and Engine Dies Without Gas
I own a 2000 Mercury Cougar with a 2.5L V6 engine. I recently received a P0172 diagnostic code, indicating over-fueling in Bank 1. Despite replacing the MAF sensor, IAC valve, TPS, fuel pump, driver module, and air filter, my car still won't start unless I continuously supply gas. If I stop feeding it gas, the engine immediately dies. I've checked all fuel lines for leaks but haven't found any issues. I'm looking for reliable troubleshooting steps to resolve this problem.
P0172 indicates over-fueling in Bank 1. This could be caused by a clogged or malfunctioning oxygen sensor, faulty fuel pressure regulator, or leaking fuel injectors. Check the fuel pressure to ensure it's within specifications and not bleeding down through the injectors. A low-pressure issue may cause the engine to run rich and die when gas is removed.