OBD Guide

B1204

Diagnosis Sensor Unit

B1204 is an OBD-II diagnostic trouble code meaning: Diagnosis Sensor Unit. Common causes: damage to the srs wiring harness, oxidation of contacts in the connectors of the diagnostic unit. Estimated repair cost: $56–167.

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

Symptoms

  • The SRS indicator on the dashboard is on
  • The passive safety system may not work in an accident.
  • Error persists after OBD-II scan

Causes

  • Damage to the SRS wiring harness
  • Oxidation of contacts in the connectors of the diagnostic unit
  • Malfunction of the sensor diagnostic unit itself
  • Problems with power or grounding of the unit
  • Incorrect programming of the unit after repair

How to Fix

  1. Check the SRS wiring harness for damage.
  2. Clean the contacts in the connectors of the diagnostic unit
  3. Check power supply and grounding of the unit
  4. Scan the system for additional errors
  5. If necessary, replace the sensor diagnostic unit
  6. Reset the error and check if it returns

Related codes

FAQ

What does the B1204 code mean?

B1204 is an OBD-II diagnostic trouble code that indicates: Diagnosis Sensor Unit

What causes a B1204 error code?

The most common causes of B1204 include: Damage to the SRS wiring harness; Oxidation of contacts in the connectors of the diagnostic unit; Malfunction of the sensor diagnostic unit itself; Problems with power or grounding of the unit.

How do I fix a B1204 diagnostic trouble code?

To fix B1204: Check the SRS wiring harness for damage.. Clean the contacts in the connectors of the diagnostic unit. Check power supply and grounding of the unit. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with B1204?

Do not drive — repair immediately

How much does it cost to fix B1204?

The estimated repair cost for B1204 is $56–167. Actual cost depends on your vehicle, location, and labor rates.

See also: Russian version · NationStat