Damaged, loose or corroded connector at the second row right seat or pillar, often disturbed by seat removal or rear seat work; Wiring fault (open circuit, chafing, short to earth or to voltage) in the circuit to the second row right restraint device; Faulty restraint device (squib or pretensioner) with out-of-range resistance; Poor contact in a shared in-line connector or clockspring-style link, where fitted, depending on model; Water ingress or corrosion in the floor or seat area affecting connectors; Internal fault in the SRS control unit's driver circuit; Previous crash damage or incorrect repair leaving a component or wiring damaged.

B0039

Second Row Right Frontal Stage 1 Deployment Control.

Generic
Body
Generic code
High severity

How this code is built

B: SystemBody
0: Defined bySAE, the same on every car
0: AreaBody area 0
39: FaultThe specific fault in that area

What it means

B0039 is a generic body code relating to the airbag (supplemental restraint system) circuit for the second row right frontal stage 1 deployment control, typically the right rear seat position restraint, such as a seat-mounted or pretensioner device. The SRS control unit monitors this squib circuit and has detected a fault such as a high or low resistance, open or short circuit, or a fault in the control unit's driver for it. The exact device fitted at this position and the precise fault condition depend on the model.

Symptoms

Airbag/SRS warning light on the dashboard
Warning light may stay on permanently or come on intermittently
SRS system may be disabled, so the device may not deploy in a crash
Possible message in the instrument cluster about a restraint fault
Car may fail an inspection due to the lit airbag light

Possible causes

Damaged, loose or corroded connector at the second row right seat or pillar, often disturbed by seat removal or rear seat worklikely
Wiring fault (open circuit, chafing, short to earth or to voltage) in the circuit to the second row right restraint devicelikely
Faulty restraint device (squib or pretensioner) with out-of-range resistancepossible
Poor contact in a shared in-line connector or clockspring-style link, where fitted, depending on modelpossible
Water ingress or corrosion in the floor or seat area affecting connectorspossible
Internal fault in the SRS control unit's driver circuitrare
Previous crash damage or incorrect repair leaving a component or wiring damagedrare

How to diagnose

Read all SRS and body codes and record them, noting whether B0039 is current or history and whether other restraint codes are present
Check any freeze frame or status data available, and whether the fault is intermittent or constant
Check whether recent work (seat removal, rear trim, upholstery, battery work) has been carried out near the second row right seat
Following the manufacturer's safe procedure, including disconnecting the battery and waiting for the stated time, visually inspect the connector and wiring at the second row right seat and pillar for damage, pins pushed back, corrosion or water
Check the wiring path back to the control unit for chafing, pinching or previous repair damage
Measure circuit resistance and check for shorts to earth or voltage on the harness using the manufacturer's specified method, never using a standard test light or meter on the device itself
Check the restraint device resistance only by a method approved by the manufacturer, as incorrect testing can deploy it
After repair, clear the codes and confirm the SRS light goes out and the fault does not return

How to fix

Repair or replace damaged wiring and terminals in line with the manufacturer's repair procedures
Clean, refit or replace corroded or loose connectors, and fix the source of any water ingress
Replace the faulty restraint device (squib or pretensioner) with the correct part
Replace a faulty shared connector or link as specified for the model
Repair or replace the SRS control unit only if testing confirms an internal fault, followed by any required setup procedure

Can I keep driving?

High severity

The restraint at this seat may not deploy in a crash while the fault is present, so it is a safety risk. The car can be driven if necessary, but have the fault repaired promptly and avoid carrying rear passengers on that side until it is fixed.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.