D373

What the Code Means

Code D373 points to a faulty signal from the steering angle sensor. The sensor is part of the SZL module (Steering Column Switch Cluster) and feeds steering position data to the DSC (Dynamic Stability Control) and ABS modules. The fault can come from contamination or a defective sensor, or from wiring and connector problems. When the code sets, DSC and ABS drop into limp mode with reduced functionality.

Symptoms

• Instrument cluster lights:
• DSC lamp on
• ABS lamp on
• Traction Control lamp on
• Occurrence conditions:
• Warnings may appear at engine start or while turning the wheel
• Vehicle behavior:
• Stability control and ABS may be disabled or work incorrectly

Diagnosis and Repair

Step 1: Read the Fault Codes

• Hook up a diagnostic scanner (ISTA, INPA) and confirm code D373 is present.
• Check for companion codes tied to the SZL or the CAN bus.

Step 2: Visual Inspection of Wiring and Connectors

• Inspect the harness running to the steering angle sensor (usually built into the SZL under the steering column).
• Look for damage, kinks, corrosion, or loose contacts.

Step 3: Clean the Sensor

• If the sensor is contaminated, carefully clean its contacts and optical elements (if applicable) with electronics cleaner.

Step 4: Replace the SZL

• If cleaning doesn't help and the wiring checks out, the SZL module likely needs replacement as a unit. The part number depends on the vehicle model.

Step 5: Calibrate the Sensor

• After replacement or cleaning, calibrate the steering angle sensor with diagnostic equipment (ISTA).

Common mistakes:

• Replacing the sensor without checking the wiring may not fix the problem.
• Skipping calibration after SZL replacement.

Secondary Problems

Ignoring code D373 can lead to:

• Total loss of DSC and ABS function, which raises the risk of a skid or loss of control in an emergency.
• Possible failure of other functions integrated into the SZL module (horn, steering column stalks, for example).
• Incorrect operation of adaptive cruise control and parking assist systems if they rely on steering position data.

Severity: High. Fix the fault as soon as possible for safety.