What this code means
B0020 may indicate an SRS concern involving the driver’s side airbag inflator circuit.
What the vehicle may do
- The SRS warning may stay on.
- The airbag system can be limited while the fault is active.
Possible fault areas
- Driver’s side airbag inflator circuit
- Right side wire harness or LSA circuit wiring
- SRS unit connector condition
- Possible SRS unit concern
Diagnostic path
Open and context
On this 2010 to 2017 Honda Accord with the 2.4 gas engine, B0020 is an SRS fault path that may involve the driver’s side airbag inflator circuit. The vehicle may keep the SRS warning on, and the airbag system can be limited while the fault is active. Broadly, this diagnosis can involve the driver’s side airbag inflator, the right side wire harness, the LSA circuit wiring, the SRS unit connector, or the SRS unit itself. We’re going to keep this calm and methodical: first prove the fault is present, then substitute the inflator with the correct simulator, then check the wiring path before condemning a module or harness.
Before testing
Before doing any SRS testing, find out if the vehicle has been in a collision. If it has, make sure the required SRS components were replaced with new parts of the correct part number and installed properly. Also make sure you’re following the SRS precautions, the general troubleshooting approach, and the 12 volt battery terminal disconnection and reconnection process. One more important point: before replacing an SRS unit, check the SRS unit software version with the HDS. If it is not current, update the software and retest before moving forward with replacement.
Prove the code is current
Start by clearing the DTCs with the HDS. Turn the vehicle to ON mode and wait for 10 seconds. Then check for DTCs again with the HDS. If B0020-13 is indicated again, the failure is duplicated and you continue with the circuit test path. If B0020-13 is not indicated, treat it as an intermittent failure and the system is OK at this time. If a different code shows up, stop and diagnose that code instead of forcing this path.
Substitute the driver’s airbag inflator
With the fault duplicated, turn the vehicle to OFF LOCK mode. Disconnect the negative cable from the 12 volt battery and wait at least 3 minutes. Then disconnect the driver’s side airbag inflator 2P connector on the right side wire harness. Connect SRS simulator lead L to the SRS inflator simulator using the 2 Ω connectors, then connect SRS simulator lead L to that driver’s side airbag inflator 2P connector on the right side wire harness. Reconnect the negative cable to the 12 volt battery, clear the DTCs with the HDS, turn the vehicle to ON mode, wait for 10 seconds, and check for DTCs again.
Read the simulator result
Now use that result to separate the inflator from the rest of the circuit. If B0020-13 is still indicated with the simulator installed, keep going into the wiring check. If B0020-13 is not indicated with the simulator installed, the fault is in the driver’s side airbag inflator. Replace the driver’s side airbag, then clear the DTC.
Check the LSA circuit for an open
If the code stayed active with the simulator in place, turn the vehicle to OFF LOCK mode again. Disconnect the negative cable from the 12 volt battery and wait at least 3 minutes. Disconnect SRS unit connector B, the 39P connector. Then disconnect the SRS inflator simulator from SRS simulator lead L, but leave SRS simulator lead L connected to the driver’s side airbag inflator 2P connector on the right side wire harness. With the vehicle in OFF LOCK mode, the driver’s side airbag inflator 2P connector disconnected from the airbag side, SRS unit connector B disconnected, and simulator lead L still connected at the right side wire harness connector, measure resistance at the SRS simulator lead L black terminal. You are looking for 1.0 Ω or less.
Use the resistance result
If the resistance is 1.0 Ω or less, the LSA positive and LSA negative wires are OK. At that point, check for a poor connection at SRS unit connector B and the SRS unit. If the connection is OK, replace the SRS unit, but only after the software check and update step has already been handled. If the DTC still does not clear after that, replace the right side wire harness. If the resistance is not 1.0 Ω or less, the fault is an open in the right side wire harness. Replace the right side wire harness, then clear the DTC.
Verify and close
Keep verification separate from the circuit testing. After the repair, clear the DTCs with the HDS, turn the vehicle to ON mode, wait for 10 seconds, and confirm B0020-13 does not return. The takeaway is simple: prove the code, isolate the inflator with the correct simulator, then let the LSA wiring resistance decide whether you are dealing with the harness side or the SRS unit side. For more diagnostic training, visit stepdiagnostics.com.
Final check
This code is best approached by proving the fault, isolating the inflator with a simulator, then checking the circuit before making a repair decision.
For more guided automotive diagnostics, visit STEP Diagnostics.
