Honda B2968 – Humidity Sensor Circuit Short to Ground

Honda-specific code — factory diagnostic data

Last updated: May 6, 2026

Definition source: Honda factory description. Diagnostic guidance is based on factory-defined fault logic for this code.

B2968 sets when the climate control module sees the humidity sensor signal pulled toward ground when it should sit at a normal in-cabin reading. The HVAC system uses humidity input to adjust airflow, recirculation, compressor cycling, and automatic defogger triggering. With an invalid signal, the module defaults to fail-safe behaviour and disables humidity-based logic.

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B2968 Quick Answer

On a Honda, B2968 means the humidity sensor signal circuit is shorted to ground. The most common causes are an internally failed sensor, water intrusion at the sensor connector, or a chafed signal wire grounded against body sheet metal. Confirm by unplugging the sensor — the code should change to an open-circuit fault if the harness is intact, which proves the sensor itself.

The Diagnostic Procedure

You will need a scan tool that reads Honda body codes (Honda HDS or an equivalent professional tool), a DVOM with min/max capture, the wiring diagram for your specific year and model, and basic hand tools to access the headliner-mounted sensor.

1. Confirm B2968 is current and capture freeze frame data. Note any concurrent climate codes — moisture intrusion at the headliner often sets several codes at once and points at the same root cause.
2. Locate the humidity sensor. On most Honda models it sits in the headliner near the rearview mirror, often integrated with a sensor cluster that includes light or rain sensing. Inspect for visible water stains, cracked housing, or a partially seated connector.
3. Unplug the sensor connector with the key off. Inspect both halves for green corrosion, bent or backed-out terminals, and moisture droplets. Reconnect, clear B2968, and recheck. If the same code returns, continue to the next step. If the code changes to a circuit-open fault, the harness is intact and the sensor itself is the problem.
4. With the sensor unplugged and the key on, backprobe the signal pin on the harness side. The signal circuit should sit at the module’s pull-up reference voltage when nothing is connected. A reading near zero volts with the sensor disconnected confirms a hard short to ground in the harness.
5. If the signal pin reads correctly with the sensor unplugged, the internal element is shorted — replace the humidity sensor and verify the climate system returns to normal humidity-based operation.
6. If the signal pin reads near zero volts with the sensor unplugged, isolate the short. Disconnect the climate control module and re-measure. If the short clears, the module-side harness or a connector pin is the fault. If the short remains, the wire between sensor and module is grounded somewhere along its run — inspect the headliner pass-through, A-pillar transitions, and any point where the harness crosses a metal bracket.
7. Repair or replace the affected harness section, clear the code, and verify normal operation. Run the climate control through AUTO mode, manual fan settings, and rear defrost to confirm humidity-based features have returned.

Common Causes

• Internally failed humidity sensor: The sensing element shorts after years of cabin moisture exposure. This is the most common single cause when the harness is undamaged.
• Water intrusion at the sensor connector: Sunroof drain blockage, windshield seal failure, or a leaking HVAC drain dumps water onto the headliner-mounted connector. Look for tide marks on the headliner fabric near the mirror.
• Chafed signal wire: The harness passes through tight A-pillar runs and headliner brackets. Years of vibration wear through insulation and ground the wire against sheet metal.
• Damaged or backed-out connector terminals: Bent pins or pushed-back terminals create a low-resistance path that mimics a hard short under certain conditions.
• Climate control module internal fault: Rare. Confirm only after the sensor and harness are proven good with a scope or DVOM.

Severity & Driving

B2968 alone does not affect drivability. The vehicle starts, runs, and drives normally. The climate control system loses its humidity-based logic, so expect more windshield fogging in rain or cold weather, less effective AUTO mode operation, and possible loss of automatic defogger triggering. On hybrid models, fuel economy may dip slightly because the compressor cannot use humidity input to optimise cycling. The code is a comfort and visibility issue rather than a safety-critical failure, but persistent fogging in poor weather warrants a prompt repair.