What this code means
B0079 may indicate that the SRS unit is detecting an open circuit or increased resistance in the driver's seat belt outer lap tensioner circuit.
What the vehicle may do
- The SRS warning indicator may be on.
- The restraint system may limit normal operation while the fault is present.
Possible fault areas
- The driver's seat belt outer lap tensioner can be involved.
- The floor wire harness can be involved.
- A poor SRS unit connector connection can be involved.
- The SRS unit itself may be involved.
Diagnostic path
Opening context and safety setup
On this 2010 to 2015 Honda Civic with the 1.8 gas engine, B0079 may mean the SRS unit is seeing an open circuit or higher than expected resistance in the driver's seat belt outer lap tensioner circuit. The SRS warning indicator may be on, and the restraint system may limit normal operation while the fault is present. Broadly, the issue can be in the tensioner, the floor wire harness, the SRS unit connection, or the SRS unit itself. Before getting into the circuit checks, start with the basic system checks. If the vehicle was in a collision, make sure the required restraint components were replaced with new parts, that the part numbers were correct, and that everything was installed properly. Also follow the SRS safety precautions and the battery disconnect and reconnect process before handling any SRS connectors.
Confirm whether the fault is active
First, verify the problem. Clear the codes with the HDS. Turn the ignition switch to ON (II), wait for 10 seconds, and check codes again with the HDS. If B0079-13 comes right back, the fault is duplicated and you move into the tensioner circuit check. If B0079-13 does not return, treat it as an intermittent fault and the system is OK at this time. If some other code is present, check what that code means first instead of chasing this path.
Isolate the tensioner from the circuit
Next, isolate the driver's seat belt outer lap tensioner. Turn the ignition switch to LOCK (0). Disconnect the negative battery cable and wait at least 3 minutes. Remove the left side B-pillar lower trim, then disconnect the driver's seat belt outer lap tensioner 2P connector on the floor wire harness. Connect the terminals of SRS simulator lead M to the SRS inflator simulator with the 2 Ω connectors, then connect simulator lead M to the driver's seat belt outer lap tensioner 2P connector on the floor wire harness. Reconnect the negative battery cable, clear the codes with the HDS, turn the ignition switch to ON (II), wait for 10 seconds, and check codes again. If B0079-13 is still indicated with the simulator in place, continue to the open wire check. If B0079-13 is not indicated, the fault points to an open or increased resistance in the driver's seat belt outer lap tensioner, and the repair path is to replace the driver's seat belt outer lap tensioner and clear the code.
Check the LLP lines through the floor harness
If the code stayed active during the simulator check, check the LLP＋ and LLP－ lines. Turn the ignition switch to LOCK (0). Disconnect the negative battery cable and wait at least 3 minutes. Disconnect SRS unit connector B, the 39P connector. Install the SRS short canceller to SRS unit connector B terminals No. 9 and No. 10, then measure resistance between the two listed test points. You are looking for 2.0－3.0 Ω between SRS unit connector B No. 9 and No. 10 under those test conditions.
Interpret the circuit result
If the measurement is 2.0－3.0 Ω, the LLP＋ and LLP－ wires are considered OK. At that point, focus on the SRS unit side: a poor connection at SRS unit connector B and the SRS unit is possible, or the SRS unit may be faulty. Check the connector-to-unit connection. Before replacing the SRS unit, check the SRS unit software version with the HDS. If the software is not the latest version, update it and retest. If the connection is OK and the software check does not resolve the issue, the repair path is to replace the SRS unit. If the code still does not clear after that, the path calls for replacing the floor wire harness. If the resistance is not 2.0－3.0 Ω, the path points to an open or increased resistance in the floor wire harness; replace the floor wire harness, then clear the code.
Verify the repair
Keep the final verification separate from the circuit testing. After the repair path is completed and the code is cleared, recheck with the HDS and confirm B0079-13 stays gone under the same key-on check. The takeaway is simple: prove whether the fault follows the tensioner, the harness, or the SRS unit connection before committing to the next repair step. For more diagnostic training, visit stepdiagnostics.com.
Final check
Confirm whether the fault follows the tensioner, the harness, or the SRS unit connection before moving to the next repair step.
For more guided automotive diagnostics, visit STEP Diagnostics.
