2000 Dodge Stratus P0172 Code: Causes, Fixes, and What to Avoid
I own a 2000 Dodge Stratus with a 2.4L Dual Overhead Cam engine. The vehicle is currently throwing a P0172 diagnostic trouble code (DTC), indicating an oxygen sensor circuit malfunction or rich fuel mixture. I took the car to a mechanic who replaced multiple components including the O2 sensor, MAP sensor, and other parts. However, after moving to Kansas, I brought it to a local repair shop that suggested replacing the Throttle Position Sensor (TPS). I installed a new TPS and drove over 60 miles—no reset of the code. I then visited CarQuest, where they used a scan tool to clear the P0172 code. After restarting the engine, the check engine light returned with the same error. I contacted a Dodge dealership in Olathe, Kansas, and was advised to install Champion spark plugs and replace the ignition wires. I previously replaced my spark plugs about 8 months ago—non-gapping, low-cost plugs (around $3.50 each). The car runs mostly fine but exhibits occasional rough idling and significantly reduced fuel economy. I'm concerned about wasting money on unnecessary repairs. Is there a logical explanation for this P0172 code? Does the suggested replacement of spark plugs or wires make sense given my vehicle's history? Ultimately, I plan to trade in this car once it reaches its end-of-life stage and would like to understand what’s actually causing the issue before continuing costly fixes.
Two key possibilities to consider: first, an EGR valve that's stuck open could cause a rich fuel condition leading to P0172. Second, if the MAP sensor is sending lower-than-actual engine vacuum signals, it can mislead the engine control unit and trigger this code. Additionally, if a replacement O2 sensor was installed with a non-compatible brand like Bosch instead of the correct used OEM part, that could also cause incorrect readings. Don't overlook timing belt issues—misalignment can lead to similar DTCs as well.