What this code means
B1658 may indicate that the keyless access control system is seeing an open circuit in the rear bumper low-frequency antenna circuit.
What the vehicle may do
- Keyless access operation near the rear of the vehicle may be affected.
- Tailgate or rear-area smart entry detection may not respond normally.
- The fault may be stored during a keyless access system self check.
Possible fault areas
- Possible rear bumper LF antenna concern.
- Possible open circuit or connector issue between the rear bumper LF antenna and the body control module.
- Possible body control module side circuit concern.
Diagnostic path
Opening context
B1658 on this CR-V points to an open-circuit fault in the rear bumper low-frequency antenna circuit for the keyless access system. In plain terms, the body control module may not be seeing the rear bumper antenna circuit the way it expects to. The vehicle may have keyless access or tailgate-area detection issues, and the possible fault areas can include the rear bumper LF antenna, its two-wire circuit, connector condition, or the body control module side of the circuit. Start with the basic system checks, and if other body communication or keyless access codes are present, check what they mean first so you do not chase this code out of context.
Confirm the code and set up the scan tool
Begin by confirming the fault with the HDS Self Check. For this diagnostic path, use the One-Push Start menu, go into the Keyless Access Control Unit, and use the Data List and Self Check functions. Before unplugging anything, identify the rear bumper LF antenna, the body control module, the circuit routing, and the body control module connector C location so your testing is done on the correct connectors.
Open-wire check on the antenna circuit
The code sets when the body control module detects a disconnection in the rear bumper LF antenna line. For the open-wire inspection, disconnect the rear bumper LF antenna 2-pin connector, then disconnect body control module connector C, the 66-pin connector. With the ignition mode shown as OFF for both sides of this check, test the EXT_TR+ circuit and the EXT_TR- circuit according to the connector terminal callouts. Each side should measure less than 1 Ω. If either open-wire check is abnormal, treat that as a circuit problem and work that circuit fault before moving on.
Body control module side check
Only move to the body control module inspection after the external circuit has tested normal. For this check, disconnect the rear bumper LF antenna 2-pin connector and perform the module internal circuit inspection at the antenna connector terminals shown for the test. The expected normal condition is voltage. If that check is abnormal, the diagnostic result is a problem with the body control module. Keep in mind this check is tied to a permanent power supply, so do not assume the feed is gone just because the vehicle mode is OFF or locked.
Antenna judgment
If the circuit inspection is normal and the body control module inspection is normal, the remaining item in this diagnostic path is the rear bumper LF antenna. At that point, the result is a problem with the rear bumper LF antenna.
Verification and takeaway
After correcting the fault you found, run the HDS Self Check again and confirm B1658 does not return. The main point on this one is to prove the two antenna wires first, then prove the body control module side, and only then call the rear bumper LF antenna. If the connector terminal callouts are not clear, pause, recheck the earlier diagnostic path, and avoid guessing at pins. For more diagnostic training, visit stepdiagnostics.com.
Final check
Prove the antenna wiring first, then the module side of the circuit, before judging the antenna.
For more guided automotive diagnostics, visit STEP Diagnostics.
