2001 Toyota MR2 Check Engine Light On: P0125, P0174, P0150, P0153, and P0440 Codes Explained
I've been relying on this forum for help with mechanical issues on my 2001 Toyota MR2, and I'm hoping someone can assist me again. The check engine light came back on in my MR2 after being off for about a month. When I took it to a code reader, I received the following five diagnostic trouble codes: - P0125: Closed Loop Fuel Control - Insufficient Coolant Temperature - P0174: System Too Lean (Bank 2) - P0150: O2 Sensor Circuit Malfunction (Bank 2 Sensor 1) - P0153: O2 Sensor Circuit Slow Response (Bank 2 Sensor 1) - P-0440: EVAP Emission Control System Malfunction I’ve previously replaced all three oxygen sensors in the vehicle, one at a time, roughly every year. I’m wondering whether these codes represent separate issues or if they are symptoms of a single underlying problem. Any insights, troubleshooting steps, or advice on how to address these codes would be greatly appreciated. Thanks, Sal
I also own a 2001 Toyota MR2 Spyder and am currently experiencing the P0440 code. I started with the common fix—replacing the gas cap with one from the Toyota dealer—but that didn’t resolve the issue. After two weeks, the check engine light remained on. I reset the system, but it came back shortly after. Interestingly, when stopped at traffic lights, the engine seems to rev higher than normal, as if the oxygen sensors are faulty—despite having replaced all three sensors just last year. This makes me suspect a problem with either the EVAP canister or vacuum lines. Has anyone else encountered this on their Toyota MR2? The canister is located behind the engine; I'm wondering if it's possible to relocate or replace it properly without major modifications.