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OBD code information sheet

https://dvireports.com/b0004

Fault codes OBDAuto
B0004

Driver Knee Bolster Deployment Control

Safe to keep driving?Caution / Repair soonArrange diagnosis soon

Arrange diagnosis soon. A limited journey may be reasonable only if the vehicle runs normally without red warnings, abnormal temperature or severe loss of power. Stop safely if serious symptoms develop.

LowCautionCritical
System groupBody & comfort

Technical explanation

Driver Knee Bolster Deployment Control. Basic catalogue definition; diagnostic details have not yet been reviewed.

Symptoms

  • System warning may illuminate

  • Affected feature may be unavailable

  • Symptoms depend on the vehicle

Possible causes

Possible causes to investigate, not a statistical ranking or a parts-replacement list.

  1. Connector or wiring fault, sensor or actuator fault, or a body control module power or ground issue

  2. Module power, ground, or connector fault

  3. Vehicle-specific mechanical or control issue

Step-by-step diagnosis

Checks

Work through the steps before replacing parts. Adapt the checks to the manufacturer’s procedure.

  1. Record all available module faults

  2. Read the body or restraint module with a compatible scan tool. Identify the affected circuit and follow the vehicle-specific safety and test procedure before touching related components.

  3. Compare results with vehicle-specific service information

  4. Verify the repair

  5. Read the body or restraint module with a compatible scan tool. Identify the affected circuit and follow the vehicle-specific safety and test procedure before touching related components.

  6. Repair the verified cause and rescan all affected modules

Check the fuses before ordering a part

An OBD code describes a detected condition; it does not tell you which part to replace. Start with the fuse for the affected circuit.

Find the fuse for your vehicleChoose the make and model, then look up the fuse position in the catalogue.

If the fuse is good, carry on like this:

  1. Check the relevant supplies and connectionsWhere the diagnostic procedure calls for electrical checks, verify supply, ground and connectors under the manufacturer’s activation conditions.
  2. Run the specified component testUse the manufacturer’s test for this code and component before deciding it has failed.
  3. Order only after the fault is demonstratedReplace a part only when the prescribed tests identify it as defective.
Check details
  • Identify the circuit and any relevant fuse: Confirm the vehicle, engine, code meaning and stored operating conditions first. A fuse link is a location aid, not evidence that the fuse caused this code. Use the specified type and rating; do not repeatedly replace a fuse that opens.
  • Check the relevant supplies and connections: Use the specified engine state, circuit conditions and expected values. Have live measurements performed by someone qualified. For non-electrical faults, follow the relevant mechanical, fluid, pressure or leak checks instead.
  • Run the specified component test: Do not apply a generic resistance range. Any resistance or continuity test requires a de-energized circuit and an isolated component, with the correct pins and temperature from the procedure. Some components need a different kind of test.
  • Order only after the fault is demonstrated: If results are normal, continue the relevant wiring, control, mechanical or intermittent diagnosis. Check for related faults and verify the repair under the required conditions. A code or a completed checklist alone does not justify replacement.
Fluke · Continuity testing

If the procedure involves airbag/SRS, pretensioners or a high-voltage system, stop DIY testing and use qualified service. Do not probe these circuits with a multimeter.

Vehicle experiences and cases

User-reported cases published after moderation. Approval does not verify the diagnosis; the same code can have different causes.

No experiences have been published for this definition yet. You can be the first to share the checks and outcome.

See all vehicle experiences

Manuals, components and vehicle guides

Find the relevant procedure in the workshop manual for your vehicle. A fault code alone does not identify a failed part, powertrain or exact schematic.

Find workshop manual / diagramRelated issues and checks

Manuals open at their original source. Exact diagram availability depends on the build year, engine and manufacturer access.

Airbags and pretensioners

General system guidance · not a confirmed diagnosis

Confirm the exact SRS definition and subtype using compatible equipment. A single code cannot establish occupant protection.

The association is based on the imported description. This information explains the system; it does not confirm a procedure for the exact code, model or engine. Verify applicability in manufacturer documentation.

Checks for this type of system

  1. Save the warning and request a specialist SRS scan.
  2. Provide accident and seat/steering-wheel repair history.

Useful diagnostic data, where available

  • Controller identity and the complete reported fault.
  • Diagnostic states read without triggering devices.

Normal values and thresholds vary by vehicle and are not assumed here.

Mistakes to avoid

  • Do not resistance-test pyrotechnic initiators.
  • Never fit resistors to conceal a restraint warning.
System-guide sources

References support general principles, not individual verification of every associated code.

Continue your research

Links to related systems, warning lights and vehicle examples.

Read the code with an OBD scanner

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