2003 Mitsubishi Eclipse Spyder P0175 Code: Diagnosis and Solutions After Multiple Repairs

If Bank 2 is running rich, a leaky fuel injector on that bank could be the culprit. Please share both banks' fuel trims for further analysis. Is your engine a 3.0L V6? Consider performing a fuel leak-down test to identify any leaking injectors.

The issue affects both Bank 1 and Bank 2, with a 3.0L V6 configuration. All fuel injectors were replaced in May—what other components could be contributing to the P0175 code?

Are you seeing both P0172 and P0175? If so, a malfunctioning MAF sensor or an over-fueling issue affecting both banks is possible. Confirm that fuel pressure is within specifications and check for leaks in the fuel pressure regulator, especially at the intake connection.

It seems the recently installed MAP sensor (aftermarket OEM model) may have quality issues. Some users report reliability problems with aftermarket replacements on this vehicle—could it be that the original OEM part is now out of stock or back-ordered?

The issue was initially resolved by replacing the MAF sensor, but within less than 24 hours, the P0175 code returned. This suggests a deeper underlying problem that may not be fully addressed by single-component replacements.

Over-fueling both banks could stem from a fuel regulator leaking at its vacuum port. Check for fuel leakage—this is a common cause in V6 Eclipse Spyders with P0175 symptoms.

The P0175 code only appears when the vehicle is idling in park after starting. The engine tends to stall if left idle for too long and requires throttle input during startup. This behavior suggests a lean/rich imbalance or ignition timing issue under low-load conditions.

As suggested, verify that the fuel regulator is not leaking from its vacuum port. Disconnect the vacuum line and let the engine run for one to two minutes—do you observe any visible fuel leakage from the regulator? This test can quickly identify a faulty fuel pressure regulator.

The actual root cause was two failing oxygen sensors. Replacing both resolved the initial misfire and lean conditions, but new codes have since reappeared.

Thanks for the update—this helps clarify the troubleshooting path.

The O2 sensor fix didn't resolve the issue. I still experience misfires when idling in park, now showing P0172, P0175, and P0300—indicating ongoing fuel or ignition problems.

Ensure fuel pressure is within manufacturer specifications. Given that multiple repairs have been attempted without improvement, consider whether the vehicle's behavior changed after each intervention. Did resetting the ECU improve performance? This could help identify if the issue is software-related or hardware-based.

Thanks for clarifying—no noticeable improvement in drivability after any repair, and the vehicle runs the same way post-intervention. The problem persists regardless of ECU reset.

I now only see P0300—after replacing the entire plenum, installing new spark plugs and wires, eliminating vacuum leaks, and completing all EVAP system repairs. The MAP sensor was also replaced. What other components could still be at fault on this 2003 Eclipse Spyder with persistent misfire codes?