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Home / DTC / B2440 — Seat Back Heater Sensor

B2440 — Seat Back Heater Sensor

Detailed page for trouble code B2440.

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Code

B2440

HUMMER B — Body

Seat Back Heater Sensor

Brand: HUMMER
Type: B — Body
Views: UK: 7 EN: 20 RU: 11
AI status
Completed
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Page language: EN

Causes

  • Open or high-resistance sensor element (broken heater/thermistor)
  • Short to ground or to battery voltage in sensor harness
  • Corroded, loose or damaged connector or terminal at the seat sensor
  • Water/moisture intrusion inside the seat causing short or loss of continuity
  • Damaged wiring harness (chafing, pinched, broken conductor)
  • Faulty seat heater assembly (sensor integrated into cushion/back)

Symptoms

  • Seat back heater does not heat or heats unpredictably
  • Seat heater indicator lamp may not illuminate or may flash/fail
  • Stored B2440 DTC (and possibly related seat heater codes) visible with scan tool
  • Inconsistent or no temperature feedback in seat heating controls
  • Possible intermittent operation that changes with seat movement or moisture exposure

What to check

  • Scan for additional related DTCs and record freeze frame/live data
  • Visually inspect seat back, connectors under seat, and wiring harness for damage, corrosion or moisture
  • Backprobe sensor connector with scan tool to view live sensor values while operating seat heater
  • Perform wiggle test of harness/connectors while monitoring live data for intermittent changes
  • Measure resistance of the sensor element at the connector with the seat removed and at ambient temperature
  • Check for short to ground and short to battery voltage on sensor circuit with multimeter

Signal parameters

  • Sensor type: temperature sensing element (thermistor) — resistance varies with temperature
  • Typical interface: low-voltage sensing circuit to seat control module (voltage signal usually 0–5 V or resistance measurement)
  • Expected behavior: resistance decreases/increases predictably with temperature; open-circuit or near-infinite resistance indicates a break; very low resistance may indicate a short
  • Exact resistance/voltage specifications vary by model — consult the vehicle service manual for manufacturer values

Diagnostic algorithm

  1. Use a scan tool to read B2440 and any related codes; note freeze frame and live data for seat back sensor.
  2. Visually inspect seat back, heater cover, and connector(s) under the seat for physical damage, corrosion, or moisture. Repair any visible issues.
  3. With ignition on, backprobe the sensor connector and observe live sensor values on the scan tool while changing seat heating settings; check for response and stability.
  4. With ignition off, disconnect the sensor connector and measure sensor resistance across the sensor terminals at ambient temperature. Compare to manufacturer spec. (If out of range, replace sensor/heater assembly.)
  5. Check continuity between the sensor connector and the seat control module connector; inspect for shorts to ground and battery with an ohmmeter/voltmeter.
  6. Repair or replace damaged wiring, terminals, or connectors. If corrosion or water ingress is present, dry and replace affected components.
  7. If wiring and sensor bench tests are within spec, inspect and test the seat/comfort control module and its connectors; reprogram or replace module only after verifying wiring/sensor integrity.
  8. Clear codes, perform functional test of seat heating, and verify the DTC does not return during operation and after road test.

Likely causes

  • Connector corrosion or poor terminal contact at the seat back sensor
  • Broken/strained wiring or pinched harness between seat and module
  • Sensor element open or resistance out of specified range due to damage or moisture
  • Seat heater assembly failure (integrated sensor)

Fault status

⚠️ Status
Seat back heater sensor circuit fault detected — sensor signal out of range (open/short/incorrect resistance).
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5 - 2.0 hours

Similar codes

B2441 B2442 B2443 B2470 B2471
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Code

B2440

Other B — Body

Passenger Sid, Side crash sensor mount fault

Brand: Other
Type: B — Body
Views: UK: 18 EN: 26 RU: 23
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Open or high-resistance sensor element (broken heater/thermistor)
  • Short to ground or to battery voltage in sensor harness
  • Corroded, loose or damaged connector or terminal at the seat sensor
  • Water/moisture intrusion inside the seat causing short or loss of continuity
  • Damaged wiring harness (chafing, pinched, broken conductor)
  • Faulty seat heater assembly (sensor integrated into cushion/back)

Symptoms

  • Seat back heater does not heat or heats unpredictably
  • Seat heater indicator lamp may not illuminate or may flash/fail
  • Stored B2440 DTC (and possibly related seat heater codes) visible with scan tool
  • Inconsistent or no temperature feedback in seat heating controls
  • Possible intermittent operation that changes with seat movement or moisture exposure

What to check

  • Scan for additional related DTCs and record freeze frame/live data
  • Visually inspect seat back, connectors under seat, and wiring harness for damage, corrosion or moisture
  • Backprobe sensor connector with scan tool to view live sensor values while operating seat heater
  • Perform wiggle test of harness/connectors while monitoring live data for intermittent changes
  • Measure resistance of the sensor element at the connector with the seat removed and at ambient temperature
  • Check for short to ground and short to battery voltage on sensor circuit with multimeter

Signal parameters

  • Sensor type: temperature sensing element (thermistor) — resistance varies with temperature
  • Typical interface: low-voltage sensing circuit to seat control module (voltage signal usually 0–5 V or resistance measurement)
  • Expected behavior: resistance decreases/increases predictably with temperature; open-circuit or near-infinite resistance indicates a break; very low resistance may indicate a short
  • Exact resistance/voltage specifications vary by model — consult the vehicle service manual for manufacturer values

Diagnostic algorithm

  1. Use a scan tool to read B2440 and any related codes; note freeze frame and live data for seat back sensor.
  2. Visually inspect seat back, heater cover, and connector(s) under the seat for physical damage, corrosion, or moisture. Repair any visible issues.
  3. With ignition on, backprobe the sensor connector and observe live sensor values on the scan tool while changing seat heating settings; check for response and stability.
  4. With ignition off, disconnect the sensor connector and measure sensor resistance across the sensor terminals at ambient temperature. Compare to manufacturer spec. (If out of range, replace sensor/heater assembly.)
  5. Check continuity between the sensor connector and the seat control module connector; inspect for shorts to ground and battery with an ohmmeter/voltmeter.
  6. Repair or replace damaged wiring, terminals, or connectors. If corrosion or water ingress is present, dry and replace affected components.
  7. If wiring and sensor bench tests are within spec, inspect and test the seat/comfort control module and its connectors; reprogram or replace module only after verifying wiring/sensor integrity.
  8. Clear codes, perform functional test of seat heating, and verify the DTC does not return during operation and after road test.

Likely causes

  • Connector corrosion or poor terminal contact at the seat back sensor
  • Broken/strained wiring or pinched harness between seat and module
  • Sensor element open or resistance out of specified range due to damage or moisture
  • Seat heater assembly failure (integrated sensor)

Fault status

⚠️ Status
Seat back heater sensor circuit fault detected — sensor signal out of range (open/short/incorrect resistance).
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5 - 2.0 hours

Similar codes

B2441 B2442 B2443 B2470 B2471
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