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AutoCodes - Generic - B0004

B0004 Code - Driver Knee Bolster Deployment Control

- Code Popularity: 18,805 Views
- Repair Importance Level: 3/3
- Repair Difficulty Level: 3/3
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By - Updated Dec 29, 2018
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|Code B0004 Possible Causes

  • Faulty Driver Knee Airbag
  • Driver Knee Airbag harness is open or shorted
  • Driver Knee Airbag circuit poor electrical connection

|How do I Fix the Code B0004?

Check the "Possible Causes" listed above. Visually inspect the related wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector's pins.

Does your Car have Safety Recalls? → Check here

|What is the Cost to Diagnose the Code B0004?

Labor: 1.0

The cost of diagnosing the B0004 code is 1.0 hour of labor. The auto repair labor rates vary by location, your vehicle's make and model, and even your engine type. Most auto repairs shops charge between $75 and $150 per hour.

|When is the Code B0004 Detected?

If the Restraints Control Module (RCM) detects a short between the driver knee air bag circuits and the circuits of another SRS component, it sets this Diagnostic Trouble Code (DTC) and the DTC of the corresponding SRS component.

|What are Code B0004 Possible Symptoms?

  • Air Bag Warning Light ON

|Code B0004 Description

The Restraints Control Module (RCM) monitors all deployable device and sensor circuits for a signal cross coupled (short) between circuits. If the RCM detects a short between the circuits of one device and another device, it will store a DTC for each of the signal cross coupled faults in memory. The RCM sends a message to the Instrument Panel Cluster (IPC) to illuminate the air bag warning indicator. When a normal loop fault is present (one loop is either shorted to battery/ground, open circuit or low resistance), then signal cross coupled diagnostics will not be active. Once the normal loop fault is repaired, then the signal cross coupled diagnostics will resume.

OBDII Code B0004 - Driver Knee Bolster Deployment Control -
B0004 Code - Driver Knee Bolster Deployment Control

|Need More Information on the B0004 Code?

Need more information on how to fix the B0004 code? Get Access to Factory Service Manuals

|Information for Specific Makes

|Need Help with the B0004 Code?

Get the B0004 code diagnosed by a professional: Find a repair shop in your area

Precautions for SRS “AIR BAG” and “SEAT BELT PRE-TENSIONER” Service

  • Never probe the electrical connectors on air bag, side air curtain modules or seat belts.
  • Never disassemble or tamper with safety belt buckle/retractor pretensioners, adaptive load limiting retractors, safety belt inflators, or probe the electrical connectors.
  • Do not use electrical test equipment to check SRS circuits unless instructed to in this Service Manual.
  • Before servicing the SRS, turn ignition switch OFF, disconnect both battery cables and wait at least 3 minutes. For approximately 3 minutes after the cables are removed, it is still possible for the air bag and seat belt pre-tensioner to deploy. Therefore, do not work on any SRS connectors or wires until at least 3 minutes have passed.
Failure to follow this instruction may result in the accidental deployment of these modules, which increases the risk of serious personal injury or death.

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