2004 Ford Explorer 4.0L Engine P0122 and P0715: Shift Issues and OBD2 Code Diagnosis
My 2004 Ford Explorer with a 4.0L engine is experiencing intermittent shifting problems and has triggered two OBD2 diagnostic codes: P0122 (Throttle Position Sensor) and P0715 (Turbine Input Shaft Sensor A). The vehicle would shift abruptly or harshly at random, and recently the Service Engine light illuminated with a wrench icon, causing the Overdrive (O/D) to shut off. When accelerating, it initially refuses to go beyond 30 mph, then suddenly shifts back to normal operation before repeating the issue. I'm wondering if these two codes are related or independent. Specifically: Is fixing the Throttle Position Sensor (TPS)—by checking wiring or replacing it—likely to resolve the P0715 error? Since both sensors are in different systems, could one failure affect the other? Additionally, I'd like to know if any other owners of this model have faced similar issues. What troubleshooting steps or repairs have proven effective? Any insights on whether a transmission rebuild or replacement is truly necessary, given that some sources suggest venting problems in the transmission are common?
To lmfisler: I've been dealing with the same issue on my 2004 Ford Explorer. I replaced two fuel rail pressure sensors (P0191 code), spending around $600–$800 in mechanic fees, but the problem persists. The vehicle stalls when transitioning from reverse to drive or during cornering—acceleration doesn't respond properly to pedal input. Even after replacing the sensor twice, the issue remains unresolved. I'm now wondering if it's a deeper transmission or electronic control module (ECM) issue rather than just a sensor failure. Have you found a permanent fix? If so, what was it? Any advice on diagnosing P0715 and P0122 in this model would be greatly appreciated. Lmatteo