B1209 Possible Causes
- Faulty Air Bag Diagnosis Sensor Unit (ACU)
- Air Bag Diagnosis Sensor Unit (ACU) harness is open or shorted
- Air Bag Diagnosis Sensor Unit (ACU) circuit poor electrical connection
How is the B1209 code repair?
Start by checking 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.Tech Notes
After a front collision, all the deployed components and the Air Bag Diagnosis Sensor Unit (ACU) must need to be replaced. If there is no collision, then the problem is with the Air Bag Diagnosis Sensor Unit (ACU)What is the cost to diagnose the B1209 code
Labor: 1.0
The cost to diagnose the B1209 code is 1.0 hour of labor. The auto repair labor rates vary widely across the country, and even within the same city. Most auto repairs shops charge between $75 and $150 per hour.
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Possible Symptoms
- Air Bag Warning Light ON
B1209 Meaning
Detects component damage resulting from a front collision, blinks or illuminates the air bag warning lamp toinform the driver. The air bag and seat belt pre-tensioners for driver and front seat passenger are operated by the decision of the Air Bag Diagnosis Sensor Unit (ACU) out signal transmitted because of the frontal collision.
The Frontal Collision Detection consists of crash zone sensor, Air Bag Diagnosis Sensor Unit (ACU), air bags and seat belt pre-tensioners for driver and front passenger.
More Information
Need more information on how to fix the B1209 code?Get Access to Factory Service Manuals
Information for specific makes
- B1209 FORD Driver Seat Back Temperature Sensor
- B1209 INFINITI Frontal Collision Detection
- B1209 LINCOLN Driver Seat Back Temperature Sensor
- B1209 MERCURY Driver Seat Back Temperature Sensor
- B1209 NISSAN Frontal Collision Detection
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.