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P0171 & P0174 Fault in 2005 Dodge Stratus Running E85 Fuel: Causes, Fixes, and Diagnostics

Model: Dodge Stratus Fault Code: P0171 Posted: 2008-01-16 08:26

I own a 2005 Dodge Stratus with 71,000 miles. The vehicle is equipped with a 2.7L flexfuel engine designed specifically for E85 operation. I purchased it about two months ago and have been running E85 exclusively since then. Two days ago, the check engine light came on. After visiting an auto parts store, I retrieved diagnostic codes: P0171 (System Too Lean Bank 1) and P0174 (System Too Lean Bank 2). I cleared these codes, and the engine appeared to run normally under regular conditions. However, last night during a quick stop at a traffic light, I noticed an unusual behavior — the engine RPM dropped sharply, followed by a brief 'gulping' sensation. The engine seemed to almost stall for a second before recovering and returning to normal RPMs. This event triggered the check engine light again. I’m considering several potential causes: - Could the P0171/P0174 codes be related to the Mass Air Flow (MAF) sensor? I'm unsure of its location or how to clean it on this model. - Since I’ve switched to E85, could this be a compatibility issue? The vehicle is a dedicated flexfuel model, but I’m concerned about fuel system performance at high loads or during rapid deceleration. - Is there an internal fuel filter in the tank that might need replacement? I know the car has not had a fuel filter changed since 71,000 miles. I have no other noticeable issues — the engine runs fine under normal driving conditions. The symptoms appear only during sudden stops or deceleration. Any insights from experienced users or mechanics on this specific model and E85 usage? Should I switch back to regular gasoline temporarily for testing? Are there known MAF sensor or fuel system limitations in 2005 Dodge Stratus flexfuel models?

Related fault codes
P0171P0174
Comments (4)
Anonymous 2008-01-16 09:32

The 2005 Dodge Stratus is a dedicated flexfuel vehicle, and it does not have an external fuel filter or a traditional Mass Air Flow (MAF) sensor. If the P0171/P0174 codes appeared after switching to E85, it's likely a compatibility issue — regular Mopar non-flex engines may struggle with E85, but flexfuel models are designed for it. However, sudden deceleration symptoms like 'gulping' could indicate fuel delivery or air intake inconsistencies. I recommend immediately switching back to regular gasoline for a few days to test if the codes disappear. If they do, then E85 is likely the root cause. For further diagnosis, consult your dealer with the VIN — parts store technicians may not have the expertise for flexfuel-specific issues.

Anonymous 2008-01-16 12:32

Thanks for the response! I appreciate you confirming that there's no external fuel filter or MAF sensor in this model. That’s helpful. Yes, it is a dedicated flexfuel vehicle — and the symptoms only occur during quick stops, not under normal driving. The 'gulping' at low RPMs after deceleration is concerning. I didn’t know that dedicated flexfuel vehicles like this one don’t have external fuel filters or MAF sensors. That makes sense — the system must rely on internal filtration and intake control. I’ll try replacing the air filter today, clear the codes again, and then run a few gallons of regular gasoline to see if the issue resolves. It’s quite cold here (below 15°F), so E85 starts can be tricky — sometimes it takes two attempts to start pure E85 in cold weather. Thanks for the tip!

Anonymous 2008-01-16 12:33

Another possibility worth checking: inspect all vacuum hoses, especially those near the intake manifold. A small leak could cause a lean condition during low-RPM deceleration, which would trigger P0171/P0174 and produce the 'gulping' sensation. Even minor leaks can significantly affect air-fuel mixture under light load conditions.

Anonymous 2008-01-16 16:56

I’d strongly recommend contacting your dealer with the vehicle’s VIN to get an accurate quote for a MAF sensor or fuel filter replacement — even if it's not standard. While some may assume these parts are common, flexfuel systems have specific requirements. A professional diagnosis using OBD2 tools and engine data is essential for reliable troubleshooting.