U0174 — Data Bus: Supplementary Restraint System (SRS) Sensor E – No Communication #

Note: The code description may vary depending on your vehicle manufacturer (OEM). Always refer to your service manual for precise terminology.

• Data Bus: SRS Sensor E – No Communication (General, SAE)
• SRS Sensor E No Communication with CAN (Honda/Acura)
• CAN Communication Fault: SRS Sensor E (Toyota/Lexus)
• Supplementary Restraint System Sensor E Communication Error (Nissan/Infiniti)

Summary of Code U0174 #

The U0174 code is an OBD-II (On-Board Diagnostics, second generation) network communication fault indicating that the vehicle’s main computer (usually the Body Control Module or Airbag Control Module) has lost communication with SRS Sensor E. SRS stands for Supplementary Restraint System, which is responsible for managing airbag deployment and other critical safety features in the event of a collision. The “data bus” refers to the vehicle’s internal communication network, often the CAN (Controller Area Network) bus, which links multiple electronic control units (ECUs). When the system cannot communicate with a specific SRS sensor, it may compromise the proper operation of airbags. This code signals a serious safety concern that should never be ignored.

Common Symptoms for Code U0174 #

If your vehicle registers the U0174 code, you may notice several warning signs. Most commonly, the airbag warning light will illuminate on the dashboard. Depending on the make and model, you might also experience additional alerts or error messages. The most significant risk is that the airbag system may not function correctly in an accident, potentially failing to deploy an airbag.

• Airbag or SRS warning light illuminated
• Warning chimes or error messages (“SRS Fault”, “Airbag System Error”)
• Other communication-related codes stored in the ECU
• Airbags or seat belt pre-tensioners may be disabled or inoperative

Probable Causes for Code U0174 #

The U0174 code is most often triggered by communication issues between the vehicle’s main control module and SRS Sensor E. These failures can result from wiring defects, connector problems, sensor faults, or, less commonly, a malfunctioning control module. It’s essential to address the most frequent causes first to avoid unnecessary part replacements.

1. Faulty or damaged wiring/connectors in the SRS Sensor E circuit
2. Failed SRS Sensor E (sensor itself is faulty or internally shorted)
3. Corroded or loose electrical connections at the SRS sensor or control module
4. Open or short circuit in the CAN bus wiring where the sensor connects
5. Malfunctioning Body Control Module (BCM) or Airbag Control Module

Step-by-Step Diagnostic for Code U0174 #

Diagnosing a U0174 code requires patience and a systematic approach. You’ll need a scan tool capable of reading OEM-level data and some basic hand tools. Always disconnect the vehicle’s battery and follow safety precautions when working around airbag systems—accidental deployment can cause injury.

• 1. Verify the code: Use an OBD-II scan tool to confirm U0174 and check for other related codes.
• 2. Inspect SRS fuses and wiring: Check all airbag and SRS-related fuses. Look for pinched, broken, or corroded wires around the SRS Sensor E location.
• 3. Examine connectors: Unplug and carefully inspect connectors at the sensor and control module for bent pins, corrosion, or loose fitting.
• 4. Test sensor resistance: If possible, use a multimeter to check resistance across the sensor terminals (refer to the repair manual for correct values).
• 5. Check CAN bus integrity: Use a scope or advanced scan tool to verify continuity and proper voltage on the communication lines (CAN High, CAN Low).
• 6. Substitute known-good sensor/module: If available, swap with a working component to isolate the faulty part, but only after ruling out wiring issues.

Possible Repairs for Code U0174 #

Once you’ve pinpointed the cause of the U0174 code, targeted repairs are the best way to restore your vehicle’s safety systems. Always clear the code and road test the vehicle after repairs to ensure the problem is resolved.

• Repair or replace damaged wiring and connectors in the SRS Sensor E circuit
• Replace faulty SRS Sensor E with an OEM or approved replacement
• Clean or tighten corroded connectors at the sensor or module
• Repair open or shorted CAN bus wires (as per wiring diagram)
• Replace the Body Control Module or Airbag Control Module if verified defective (rare)

Is It Safe to Drive with Code U0174? #

No, it is not recommended to drive your vehicle with the U0174 code present. This code directly affects the airbag system, which may not deploy in the event of a crash. Not only does this compromise your safety, but driving with a disabled SRS system can be illegal in some regions. Have the issue diagnosed and repaired as soon as possible to ensure your protection.

Vehicles Most Commonly Affected by Code U0174 #

While the U0174 code can appear in any modern vehicle using OBD-II protocols, it’s more frequently reported in certain models, particularly those with complex SRS/CAN networks or known connector vulnerabilities.

• Honda and Acura late-model sedans and SUVs
• Toyota and Lexus vehicles (especially 2012–2020 models)
• Nissan and Infiniti crossovers and sedans
• Some GM (Chevrolet, GMC, Cadillac) models with advanced SRS systems
• European brands (Mercedes-Benz, BMW) with multi-sensor airbag arrays

Common Mistakes & Best Practices for Code U0174 #

Misdiagnosis is common with network codes like U0174, as technicians sometimes overlook the basics or skip steps. Following best practices prevents repeated failures and unnecessary expenses.

• Assuming the SRS sensor is faulty without checking wiring or connectors first
• Ignoring other communication codes that may point to a broader CAN bus issue
• Clearing the code without fixing the root cause (the warning will return)
• Not disconnecting the battery before working on airbag circuits (risk of accidental deployment)
• Using non-OEM or low-quality replacement parts

Quick FAQ for Code U0174 #

Here are answers to some common questions about U0174 to help you make informed decisions.

• Q: Can I just clear the code and keep driving?
  A: No. Clearing the code without addressing the root problem will not restore SRS function, and your airbag system may remain disabled.
• Q: Is this a dealer-only repair?
  A: Not always. Skilled independent shops with OEM-level scan tools can diagnose and fix most U0174 issues, but some cases (like module replacement) may require dealer programming.