OBD Guide

B1904

Air Bag Crash Sensor 2 Feed/Return Circuit Failure

B1904 is an OBD-II diagnostic trouble code meaning: Air Bag Crash Sensor 2 Feed/Return Circuit Failure. Common causes: open or short circuit in shock sensor 2 circuit, corrosion of contacts or connectors. Estimated repair cost: $56–167.

Severity
🔴 High
Can you drive?
Do not drive — repair immediately
Approx. repair cost
$56–167 (est.)

Symptoms

  • The passive safety system fault indicator is on
  • Airbags may not deploy in a crash
  • Error B1904 is stored in the SRS module memory

Causes

  • Open or short circuit in shock sensor 2 circuit
  • Corrosion of contacts or connectors
  • Shock sensor 2 malfunction
  • Wiring harness damage
  • SRS control module problem

How to Fix

  1. Check the integrity of the shock sensor 2 circuit (open/short circuit)
  2. Inspect connectors and contacts for corrosion or damage
  3. If necessary, replace shock sensor 2
  4. Check wiring harness for damage
  5. Scan the SRS module for other errors
  6. Reset the error and check for its reappearance

Related codes

FAQ

What does the B1904 code mean?

B1904 is an OBD-II diagnostic trouble code that indicates: Air Bag Crash Sensor 2 Feed/Return Circuit Failure

What causes a B1904 error code?

The most common causes of B1904 include: Open or short circuit in shock sensor 2 circuit; Corrosion of contacts or connectors; Shock sensor 2 malfunction; Wiring harness damage.

How do I fix a B1904 diagnostic trouble code?

To fix B1904: Check the integrity of the shock sensor 2 circuit (open/short circuit). Inspect connectors and contacts for corrosion or damage. If necessary, replace shock sensor 2. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with B1904?

Do not drive — repair immediately

How much does it cost to fix B1904?

The estimated repair cost for B1904 is $56–167. Actual cost depends on your vehicle, location, and labor rates.

See also: Russian version · NationStat