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Engine-Codes – Generic – P1635

P1635 Code - Tire / Axle Ratio Out of Acceptable Range

Quick Answer

The P1635 diagnostic trouble code indicates that the tire or axle ratio of the vehicle is out of an acceptable range. Common causes include Installation of incorrect tire size, Incorrect gear ratio in the differential, Faulty speed sensor. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means
P1635 indicates Tire / Axle Ratio Out of Acceptable Range.
Common causes
Common causes include Installation of incorrect tire size, Incorrect gear ratio in the differential, Faulty speed sensor.
Severity
High - diagnose this code as soon as possible.
Can I drive?
Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.
What is this?
Table of contents Created and updated by William Orellana on Aug 30, 2024
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Code P1635 Description

The P1635 diagnostic trouble code indicates that the tire or axle ratio of the vehicle is out of an acceptable range. The tire/axle ratio is an important parameter that affects the overall performance of the vehicle, including acceleration, fuel efficiency, and speedometer accuracy. When this ratio is not within the specified range, it can lead to irregularities in the vehicle's operation.

OBDII Code P1635 - Tire / Axle Ratio Out of Acceptable Range
P1635 Code - Tire / Axle Ratio Out of Acceptable Range

Common Causes of P1635

  1. Installation of incorrect tire size
  2. Incorrect gear ratio in the differential
  3. Faulty speed sensor
  4. Wiring issues in the speed sensor circuit
  5. ECM software malfunction

Symptoms of P1635

  1. Inaccurate speedometer readings
  2. Poor fuel efficiency
  3. Difficulty accelerating smoothly
  4. Unusual noises coming from the drivetrain
  5. Increased wear on tires or other drivetrain components

How to Fix P1635

  1. Check and correct tire size: Ensure that the tires on the vehicle match the manufacturer's recommended size.
  2. Inspect and adjust gear ratio: Verify that the gear ratio in the differential is correct and adjust if necessary.
  3. Test and replace speed sensor: Check the speed sensor for proper operation and replace if faulty.
  4. Check wiring: Inspect the wiring in the speed sensor circuit for any damage or corrosion and repair as needed.
  5. Reset ECM: Reset the Engine Control Module (ECM) to clear the trouble code and relearn the correct tire/axle ratio.

Cost to Fix P1635

The typical repair costs for addressing a P1635 code can vary depending on the specific cause of the issue. In general, the cost for parts and labor to resolve this problem can range from $100 to $500. It's important to note that diagnostic time and labor rates at auto repair shops can differ, so it's recommended to check with local shops for a more accurate estimate.

What does this mean?

Tech Notes for P1635

On some Ford models, the Powertrain Control Module (PCM) DTC P1635 indicates that the tire size or axle ratio programmed into the PCM is not correct for the PCM calibration present in the PCM. This DTC can be caused by a modified PCM calibration, or a tire size or axle ratio programmed into the PCM that does not match the vehicle's build information.

After a new Powertrain Control Module (PCM) has been installed, the Vehicle Identification (VID) block must be programmed into the PCM.

Need more information about the P1635 code?

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Code P1635 Information for Specific Makes

About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

Frequently Asked Questions about P1635 Code

1. What are the common symptoms of OBDII code P1635 (Tire / Axle Ratio Out of Acceptable Range)?

- Common symptoms include poor fuel economy, difficulty shifting gears, and illuminated warning lights on the dashboard.

2. What are the possible causes of OBDII code P1635?

- The code P1635 can be triggered by incorrect tire size, axle ratio changes, faulty speed sensors, or issues with the vehicle's computer system.

3. How can I diagnose the cause of OBDII code P1635?

- To diagnose the cause of P1635, you can check the tire size and axle ratio specifications in the vehicle's manual, inspect the speed sensors, and use a diagnostic tool to read the code and gather more information.

4. Can driving with OBDII code P1635 cause further damage to my vehicle?

- Continuing to drive with P1635 may result in poor performance, reduced fuel efficiency, and potential damage to the drivetrain components over time.

5. How can I repair OBDII code P1635?

- The most common solutions for P1635 include recalibrating the tire size and axle ratio settings, replacing faulty speed sensors, and resetting the vehicle's computer system with a diagnostic tool.

6. Is it safe to ignore OBDII code P1635?

- Ignoring P1635 can lead to decreased fuel efficiency and potential drivability issues, so it is recommended to address the underlying cause promptly.

7. Can I reset OBDII code P1635 without fixing the underlying issue?

- Resetting the code without addressing the root cause may temporarily turn off the warning light, but the issue will likely resurface until the problem is resolved.

8. Will fixing OBDII code P1635 improve my vehicle's performance?

- Resolving P1635 by correcting tire size and axle ratio discrepancies and fixing related issues can lead to improved fuel efficiency, smoother shifting, and overall better performance.

9. How long does it typically take to repair OBDII code P1635?

- The repair time for P1635 can vary depending on the underlying cause, but it may take anywhere from a few minutes to a few hours, depending on the complexity of the issue.

10. Can a mechanic help me fix OBDII code P1635?

- Yes, a qualified mechanic can diagnose and repair the underlying issues causing P1635, ensuring proper calibration of tire size, axle ratio, and speed sensors to resolve the code.

Discuss the causes and fixes for P1635 OBDII Code

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  • I HAVENT CHANGED ANY PARTS OUT IN MONTHS AND IM GETTIN P1635 , 0710 & P0713 CODES AND MY TRANSMISSION IS SHOWING -068 DEGREES ON THE SCT TUNER W/CUSTOM TUNES THAT IVE BEEN RUNNING WITH NO ISSUES FOR THREE YRS. I DID PUT TRUCK IN 4X4 YESTERDAY AT WORK . STARTED HOME AFTER WORK AND OUT OF THE BLUE TRANSMISSION LIGHT CAME ON AND SOUNDED AS THOUGH TRANSMISSION WAS SLIPPING OR SOMETHING. NO POWER ,WRENCH LIGHT ON AND NO TEMP ON OIL TEMP GAUGE ON DASH.

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