The P0729 code is an OBD-II trouble code that indicates a Gear 6 Incorrect Ratio. This code is triggered when the Transmission Control Module (TCM) detects that the transmission is not engaging the correct gear as expected.
What Does the P0729 Code Mean?
OBD-II Code P0729 is defined as a Gear 6 Incorrect Ratio. The TCM relies on inputs from both the Input Speed Sensor and the Output Speed Sensor to determine the correct gear engagement. If there is a discrepancy between these signals, the TCM will set the P0729 code.
What Causes the P0729 Code?
Several factors can trigger the P0729 code, including:
- Internal transmission failure
- Powertrain Control Module (PCM) failure
- Transmission Control Module (TCM) failure
- Low transmission fluid level
- Transmission valve body failure
- Wiring issues
What Are the Symptoms of the P0729 Code?
Drivers experiencing the P0729 code may notice:
- Increased fuel consumption
- Transmission may not shift properly
How Serious Is the P0729 Code?
The P0729 code is considered urgent. It indicates significant malfunctions that can potentially cause severe damage to the vehicle or pose risks to driver and passenger safety. Immediate attention is recommended to prevent further complications.
How to Diagnose the P0729 Code
Proper diagnosis of the P0729 code involves a comprehensive approach:
- Use an OBD-II scanner to confirm the P0729 code and check for any additional codes.
- Inspect the wiring and connectors related to the Input and Output Speed Sensors.
- Check the transmission fluid level and condition.
- Test the Input Speed Sensor and Output Speed Sensor for proper operation.
- Examine the transmission for any internal issues.
Common Repairs for the P0729 Code
Repairs may include:
- Automatic Transmission Fluid/Filter Change
- Replacing faulty Input or Output Speed Sensors
- Repairing or replacing wiring and connectors
- Fixing internal transmission issues or replacing the TCM
How Much Does It Cost to Fix the P0729 Code?
The cost to fix the P0729 code can vary widely based on the specific issue and the make and model of the vehicle. On average, repairs may range from $100 to $1,500, depending on whether it involves simple fluid changes or more complicated repairs such as transmission replacement.
Can I Fix the P0729 Code Myself?
While some aspects of diagnosing and fixing the P0729 code can be done by a knowledgeable DIYer, it is recommended to consult with a professional mechanic. Proper diagnosis and repairs require specialized tools and expertise to ensure the problem is accurately identified and resolved.
i have a 2020 ford f250 6.7l its all stock no modifications. i have a p0729 gear 6 incorrect ratio. it is intermittent especially when the truck reaches operating temperatures. drives good when cold but also i hvae a egr excessive flow. i wonder if there is a relationship btn the two.
On a 2020 F250 6.7L, you are running the 10R140 10-speed, and P0729 on that transmission has a well-documented pattern worth checking before anything else.
In fact, 2020MY 10R140s were covered under a TCM software TSB that addressed exactly this kind of intermittent, heat-related shifting fault. The calibration in early 2020 units was not fully dialed in from the factory, and a reflash resolved it for a lot of trucks. Given that yours shows up intermittently and specifically at operating temperature, this should be your first stop. Have your TCM software level checked against the current calibration before you do anything else.
If the TCM is already current, then it moves to the usual suspects for a 6th gear ratio code: transmission fluid condition and level (10R140 uses a fluid rated for the life of the transmission, but level and contamination still matter), and the 6th gear shift solenoid. A pressure or flow test on that circuit will tell you if it is hydraulic or electrical.
As for the EGR excessive flow code, I would treat that as a separate issue. Excessive EGR flow typically points to a stuck-open EGR valve or actuator problem, and that runs through the PCM, not the TCM. There is no documented shared cause between EGR flow and 6th gear ratio faults on the 6.7. It’s most likely a coincidence of two age-related issues surfacing around the same time rather than one causing the other. Worth confirming the EGR valve is moving freely and not sticking before you write it off as unrelated, but I would not chase a connection between the two systems that isn’t there.
Start with the TCM software level. That is the most likely single fix for the P0729 specifically.