B1967

A/C Post Heater Sensor Circuit Short To Ground

Body Engine Cooling A/C Climate Sensor 🟢 Low — Fix at next service ✅ Safe to Drive
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What This Actually Means

In plain language — no jargon

The A/C post-heater sensor has a short circuit to ground, meaning the electrical wire is touching metal chassis instead of sending a proper signal. It's like a water hose with a hole—the signal leaks out instead of reaching its destination.

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Symptoms You May Notice

3 known symptoms for this code
A/C system not functioning or blowing warm air
Check Engine Light or climate control warning illuminated
Inconsistent temperature control in cabin
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How Your ECU Detects This

Technical sensor logic and voltage thresholds

The ECU monitors the post-heater temperature sensor's voltage output to regulate A/C blend door position and heating/cooling cycles. When the sensor shorts to ground, the voltage drops abnormally low (near 0V), triggering a fault. The ECU expects a voltage signal between 0.5V–4.5V depending on actual temperature.

Voltage & Parameter Thresholds

ParameterNormal RangeFault Condition
Sensor Voltage 0.5–4.5V (proportional to temperature) <0.2V or short-to-ground detected
Resistance 2k–100k Ohms (temperature-dependent) <500 Ohms or shorted
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Diagnostic & DIY Fix Guide

Check these in order — from cheapest to most complex
1
Wiring harness connector at sensor
Inspect and reseat the connector firmly; corrosion or loose pins often cause false shorts.
2
Wiring insulation and routing
Check the sensor wire for cuts, abrasion, or pinch points where it may contact metal; repair or reroute as needed.
3
A/C post-heater temperature sensor
Replace the sensor if it shows internal short or failed resistance test with multimeter.
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When to See a Professional Mechanic

Not all fault codes are safe to DIY

Code B1967 is a low-severity fault. Your vehicle is generally safe to drive to a workshop for diagnosis. However, do not ignore it indefinitely — low-severity codes often indicate developing problems that become expensive if neglected. Book a diagnostic appointment within 2–4 weeks. If you notice any additional symptoms (rough running, power loss, unusual smells), treat it as higher priority.

Safety note: OBD-II codes identify the system or circuit where a fault was detected — they do not always identify the exact failed component. A professional mechanic using live sensor data will diagnose the root cause more accurately than replacing parts based on the code alone.
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How to Clear Code B1967

What happens after you fix the fault

Once the fault is repaired, B1967 can be cleared using any OBD-II scanner. Connect the scanner, navigate to "Clear Codes" or "Erase DTCs," and confirm. The check engine light turns off immediately.

The code will return if the root cause was not actually fixed. The ECM re-detects the fault within 1–3 drive cycles and sets the code again.

✅ Safe to Clear When
  • Fault has been diagnosed and repaired
  • You want to confirm the repair worked
  • Code appeared after a sensor was cleaned
⚠️ Do Not Clear When
  • Preparing for an emissions/PUC test
  • Root cause is still undiagnosed
  • Check engine light is flashing
Emissions test note: Clearing codes resets OBD readiness monitors. Most vehicles need 50–100 km of mixed driving before monitors complete. Do not clear codes immediately before an emissions or PUC inspection.