C0138 - Understanding the Steering Angle Sensor Fault in 2010-2018 Ford Focus and Other Models

Quick Answer

C0138 means: DTC C0138 indicates a fault with the Steering Angle Sensor.

Fix: Check and replace faulty components Cost: $150 - $300 Time: 90-180 minutes

Can I drive with C0138? Address immediately to maintain vehicle stability and safety.

Common Questions

What does C0138 mean and how does it affect my car?

DTC C0138 indicates a problem with your vehicle's Steering Angle Sensor, which is crucial for maintaining stability and traction. If this sensor fails, you may experience difficulty steering, increased tire wear, and your stability control features may not work properly. It's important to address this issue as it can lead to unsafe driving conditions.

What are the most common causes of C0138 and how much does it cost to fix?

The most common cause of the C0138 code is a faulty Steering Angle Sensor, which typically costs between $150 and $300 to replace. Other causes include damaged wiring or connectors, incorrect calibration, and software issues, which can complicate repairs and may add to the cost.

Can I drive my car with C0138 or should I stop immediately?

Driving with the C0138 code can be risky. It may lead to unpredictable steering behavior, especially in emergency situations. It's advisable to have the issue checked and repaired as soon as possible to ensure your safety.

How can I diagnose C0138 myself using GeekOBD APP?

You can utilize the GeekOBD APP to scan for codes and review freeze frame data for context. Follow the app's instructions to check the Steering Angle Sensor's live data, which can help you understand whether the sensor is functioning correctly before deciding to replace it.

What vehicles are most commonly affected by C0138?

The C0138 code is often reported in vehicles like the 2010-2018 Ford Focus, 2012-2016 Toyota Camry, and various models from Honda, Chevy, and Nissan. It's worth checking for any recalls or Technical Service Bulletins (TSBs) related to the steering system in these vehicles.

How can I prevent C0138 from happening again?

Regular maintenance of your vehicle's steering system, including inspections and timely repairs, can help prevent future occurrences of C0138. Additionally, recalibrating the Steering Angle Sensor after any significant steering system service can help maintain its functionality.

What is C0138?

The DTC C0138 diagnostic trouble code indicates a malfunction in the Steering Angle Sensor (SAS), which is critical for the vehicle's stability control system. This sensor measures the angle of the steering wheel and sends this information to the vehicle's onboard computer. When the SAS is not functioning properly, it can lead to issues with the vehicle's ability to maintain traction and stability, especially during turns or on slippery surfaces. Drivers may notice erratic handling, an illuminated warning light on the dashboard, or even a complete loss of stability features. In modern vehicles, such as the 2013 Ford Focus or 2015 Honda Accord, the SAS is integral to various advanced driver-assistance systems (ADAS) like Electronic Stability Control (ESC) and Anti-lock Braking System (ABS). If left unchecked, a malfunctioning SAS can lead to increased wear on tires and suspension components due to improper handling, potentially causing unsafe driving conditions. Therefore, it is essential for car owners to address this code promptly to ensure their vehicle operates safely and efficiently.

System: C - Chassis (ABS, Steering, Suspension)

Symptoms

Common symptoms when C0138 is present:

  • The 'Check Engine' light remains illuminated, indicating a fault detected by the onboard computer.
  • The vehicle may experience erratic steering response, making it difficult to maintain a straight path.
  • Drivers may notice a decrease in fuel efficiency, as the stability system may engage more often, affecting overall performance.
  • The traction control system warning light might appear, signaling issues with stability control features.
  • Unusual noises from the steering column could occur, indicating sensor or wiring issues.

Possible Causes

Most common causes of C0138 (ordered by frequency):

  1. The most common cause is a faulty Steering Angle Sensor, which occurs in about 60% of cases due to wear and tear or electrical issues.
  2. Another common cause is damaged wiring or connectors, which can lead to intermittent signals sent to the vehicle's computer.
  3. Incorrect sensor calibration can also trigger this code; it's crucial to recalibrate after any steering system service or replacements.
  4. Less commonly, a malfunction in the vehicle's ABS module may cause C0138, leading to complex diagnostic situations.
  5. In rare cases, software glitches in the vehicle's control module can misinterpret data from the SAS, causing false codes.

C0138 Repair Costs

Cost Breakdown by Repair Type

Replacement of Steering Angle Sensor

Replacement of the faulty Steering Angle Sensor with a new OEM part.

  • Total: $150 - $300
  • Success rate: 90%
Calibration Service

Professional calibration of the new sensor to ensure proper function.

  • Total: $50 - $100
  • Success rate: 95%
Money-Saving Tips for C0138
  • Start with the most common and least expensive repairs first
  • Use GeekOBD APP to confirm diagnosis before replacing expensive parts
  • Consider preventive maintenance to avoid future occurrences
  • Compare prices for OEM vs aftermarket parts based on your needs
  • Address the issue promptly to prevent more expensive secondary damage

Diagnostic Steps

Professional C0138 Diagnosis Process

Follow these systematic steps to accurately diagnose C0138. Each step builds on the previous one to ensure accurate diagnosis.

Step 1: Step 1: Perform an initial visual inspection of the steering column and wiring for any obvious damage or loose connections (5-10 minutes)

Step 1: Perform an initial visual inspection of the steering column and wiring for any obvious damage or loose connections (5-10 minutes).

GeekOBD APP Tip: Use GeekOBD APP to monitor real-time data during this diagnostic step for accurate results and professional-grade analysis.
Step 2: Step 2: Use the GeekOBD APP to perform an OBD2 scan to retrieve all codes and freeze frame data, helping understand the context of the fault (10-15 minutes)

Step 2: Use the GeekOBD APP to perform an OBD2 scan to retrieve all codes and freeze frame data, helping understand the context of the fault (10-15 minutes).

GeekOBD APP Tip: Use GeekOBD APP to monitor real-time data during this diagnostic step for accurate results and professional-grade analysis.
Step 3: Step 3: Conduct component testing on the Steering Angle Sensor using a multimeter to check for proper voltage and resistance (20-30 minutes)

Step 3: Conduct component testing on the Steering Angle Sensor using a multimeter to check for proper voltage and resistance (20-30 minutes).

GeekOBD APP Tip: Use GeekOBD APP to monitor real-time data during this diagnostic step for accurate results and professional-grade analysis.
Step 4: Step 4: If a fault is found, replace the sensor and perform a system function test to verify that the sensor operates correctly and reset all codes (10-15 minutes)

Step 4: If a fault is found, replace the sensor and perform a system function test to verify that the sensor operates correctly and reset all codes (10-15 minutes).

GeekOBD APP Tip: Use GeekOBD APP to monitor real-time data during this diagnostic step for accurate results and professional-grade analysis.
Step 5: Step 5: Execute a road test to ensure the steering system is functioning correctly under various driving conditions (15-20 minutes)

Step 5: Execute a road test to ensure the steering system is functioning correctly under various driving conditions (15-20 minutes).

GeekOBD APP Tip: Use GeekOBD APP to monitor real-time data during this diagnostic step for accurate results and professional-grade analysis.

Important Notes

  • Always verify the repair with GeekOBD APP after completing diagnostic steps
  • Clear codes and test drive to ensure the problem is resolved
  • Address underlying causes to prevent code recurrence

Real Repair Case Studies

Case Study 1: Repair of C0138 in a 2015 Ford Focus

Vehicle: 2015 Ford Focus, 45,000 miles

Problem: Driver reported steering instability and dashboard warning lights.

Diagnosis: After scanning with the GeekOBD APP, DTC C0138 was confirmed. A visual inspection revealed a damaged wiring harness.

Solution: Replaced the Steering Angle Sensor and repaired the wiring harness. Calibration was performed to ensure proper functionality.

Cost: $250 (sensor $200, labor $50)

Result: The vehicle's handling improved significantly, and no further warning lights appeared after the repair.

Case Study 2: Addressing C0138 in a 2016 Honda Accord

Vehicle: 2016 Honda Accord, 60,000 miles

Problem: Customer experienced traction control warning light and intermittent steering issues.

Diagnosis: Diagnostic testing revealed C0138. The SAS was tested and found to be malfunctioning.

Solution: The Steering Angle Sensor was replaced, and the system was recalibrated using the GeekOBD APP.

Cost: $300 (sensor $250, calibration $50)

Result: Post-repair, the vehicle's stability control functioned correctly, and the customer reported improved driving experience.

Diagnose C0138

Use GeekOBD APP for professional diagnosis!

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  • Professional-grade analysis
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Code Information

Code: C0138
System: Chassis (ABS, Steering, Suspension)
Severity: HIGH
Category: Chassis Codes