What this code means
B0029 may indicate an open or increased resistance condition in the right side curtain airbag inflator circuit.
What the vehicle may do
- The SRS warning light may be on.
- The airbag system may limit normal operation while the fault is present.
- The fault can be intermittent.
Possible fault areas
- Right side curtain airbag inflator circuit
- Floor harness wiring for the curtain airbag circuit
- SRS unit connector area
- SRS unit
Diagnostic path
Opening context
On this Civic, B0029 points to a possible open or increased resistance condition in the right side curtain airbag inflator circuit. The driver may see the SRS warning light, and the system may limit normal airbag operation while the fault is present. Broadly, this can involve the right side curtain airbag inflator circuit, the floor harness wiring, the SRS unit connector area, or the SRS unit itself. Because this is an SRS circuit, start carefully and do not skip the basic safety checks.
Before testing
Before getting into the circuit checks, find out whether the vehicle has been in a collision. If it has, make sure the required SRS components were replaced with new, correct-part-number components and installed properly. Also handle the SRS and battery-disconnect procedures correctly before touching connectors. One more important point: before replacing the SRS unit, check its software version with the HDS. If it is not current, update the SRS unit software and retest before condemning the unit.
Verify the fault first
Start by clearing the DTCs with the HDS. Turn the ignition switch to ON (II), wait for 10 seconds, and check codes again. If B0029-13 comes right back, the fault is duplicated and you move into circuit isolation. If it does not come back, treat it as an intermittent condition and the system is OK at this time. If another code is present instead, check what that code means first.
Isolate the right side curtain airbag inflator
Next, turn the ignition switch to LOCK (0). Disconnect the negative battery cable and wait at least 3 minutes. Remove the right side C-pillar trim, then disconnect the right side curtain airbag inflator 2P connector on the floor wire harness. Connect the terminals SRS of simulator lead L to the SRS inflator simulator with the 2 Ω connectors, then connect SRS simulator lead L to the right side curtain airbag inflator 2P connector on the floor wire harness. Reconnect the negative battery cable, clear the DTCs with the HDS, turn the ignition switch to ON (II), wait for 10 seconds, and check for B0029-13 again. If the code is still indicated with the simulator in place, keep going into the harness check. If the code is not indicated, the path points to an open or increased resistance in the right side curtain airbag inflator, and replacement of the right side curtain airbag is supported by this test result.
Check the RCA circuit for an open
For the open-wire check, turn the ignition switch back to LOCK (0). Disconnect the negative battery cable and wait at least 3 minutes. Disconnect SRS unit connector B. Now disconnect the SRS inflator simulator from SRS simulator lead L, but do not disconnect SRS simulator lead L from the right side curtain airbag inflator 2P connector on the floor wire harness. Measure resistance at the SRS simulator lead L black terminal with the test focused on the RCA＋ and RCA－ lines. The decision point is 1.0 Ω or less.
Use the resistance result to choose the next path
If the measurement is 1.0 Ω or less, the RCA＋ and RCA－ wires are considered OK. At that point, inspect the connection between SRS unit connector B and the SRS unit. If the connection is OK, replacement of the SRS unit is supported, but only after the software-version check and retest mentioned earlier. The follow-up wording after that point is incomplete, so if the code still does not resolve, pause, recheck the earlier diagnostic path, and avoid guessing. If the measurement is not 1.0 Ω or less, the path points to an open or increased resistance in the floor wire harness, and replacement of the floor wire harness is supported.
Verify the repair
Keep verification separate from the fault isolation. After the supported repair path is completed, clear the DTCs with the HDS, turn the ignition switch to ON (II), wait for 10 seconds, and confirm B0029-13 stays gone. The key takeaway is to prove the fault first, isolate the inflator with the simulator, then use the RCA circuit resistance result to separate an inflator issue, a floor harness issue, or an SRS unit connection or unit issue. For more diagnostic training, visit stepdiagnostics.com.
Final check
This diagnostic path may separate an inflator-side issue from a harness issue or an SRS unit connection concern by using a simulator and a circuit resistance check.
For more guided automotive diagnostics, visit STEP Diagnostics.
