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2005 Intrepid with P0731 and P0432: Gear Ratio and Catalytic Converter Issues Explained

Model: Intrepid Fault Code: P0432 Posted: 2006-07-18 09:52

I'm experiencing two diagnostic trouble codes on my 2005 Intrepid: P0731 (Gear 1 ratio incorrect) and P0432 (Main catalytic converter below threshold, Bank 2). Can anyone provide insight into the root causes and fixes? The P0432 code — indicating the main catalytic converter is not performing at expected levels — often points to issues like a failed oxygen sensor, exhaust leak before the converter, or a failing converter itself. Is this simply a case of 'catalyst plugged, replace it' or could there be another underlying cause? For P0731, I'm less certain. The gear ratio error may stem from problems with speed sensors (input or output), wiring issues, valve body malfunction, or transmission slippage. My vehicle occasionally feels like it's in a higher gear when accelerating from low speeds — there’s no noticeable shifting failure, just a lag at the bottom end. I’ve had no recent work done on the car and no prior history of mechanical trouble. Any advice would be greatly appreciated. Thanks!

Related fault codes

P0432P0731

Comments (6)

Anonymous 2006-07-18 10:00

The P0731 code is typically caused by issues with input or output speed sensors, wiring faults, valve body problems, or transmission slippage. If left unaddressed, it can lead to severe transmission damage. The P0432 code may result from a failed converter, faulty oxygen sensors (O2), or an exhaust leak upstream of the catalytic converter. To diagnose accurately: check if the transmission is shifting properly and whether the speedometer is functioning correctly. Has any work been done recently? A professional scan can detect limp mode — where the transmission defaults to 2nd gear — by reading sensor data. If you don’t have access to a diagnostic scanner, consider visiting a dealership or certified shop. Input and output sensors are generally under $30 each and should be replaced if faulty. Also, check transmission fluid condition — color and consistency matter. I’ve seen many cases where replacing these sensors resolves the issue. Good luck and please keep us updated!

Anonymous 2006-07-18 10:05

No recent repairs have been performed on the vehicle. There’s no history of mechanical issues. The car occasionally feels like it's in a higher gear when accelerating from low speeds — no harsh shifts or stalling, just a noticeable lag at idle and low RPMs.

Anonymous 2006-07-18 10:46

Yes, the transmission is programmed to shift into second gear when a fault is detected. This is likely due to a faulty input or output speed sensor circuit or one of the sensors themselves. If ignored, it can lead to complete transmission failure. With an advanced OBD2 scanner, you can detect if the vehicle is in limp mode and monitor actual sensor readings. Without such equipment, I recommend consulting a certified mechanic or dealership for diagnosis. Input and output speed sensors are typically located externally on the driver’s side of the transmission — they screw into the transmission casing. Make sure to purchase OEM or factory-approved parts from the dealer to ensure compatibility. Fluid condition is also critical — check if it's dark, burnt, or low. I’ve replaced these sensors multiple times at dealerships for similar symptoms.

Anonymous 2006-07-18 12:45

Could you please share your Intrepid’s model year, engine size, and current mileage? This information helps narrow down potential causes specific to the vehicle's generation and usage.

Anonymous 2006-07-18 18:07

Thanks for the helpful input. Multiple sources suggest replacing the speed sensors — I’m planning to do that. Are these sensors located inside or outside the transmission? I recently replaced a shift sensor in my Suburban, which was situated inside the valve body within the transmission pan — is this the same type of sensor?

Anonymous 2006-07-19 05:55

No, those sensors are not inside the pan. They screw directly into the outside of the transmission on the driver’s side. Always ensure you get the correct OEM or factory-approved sensors from a dealership to avoid compatibility issues.