B1287

Servo Motor Potentiometer Airintake Left Circuit Short To Ground

Body Fuel and Air Metering Air intake servo control 🟢 Low — Fix at next service ✅ Safe to Drive
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What This Actually Means

In plain language — no jargon

The intake air control servo motor's position sensor has shorted to ground, meaning the electrical signal is stuck at zero instead of varying normally. Think of it like a volume dial that's broken and stuck at mute.

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Symptoms You May Notice

3 known symptoms for this code
Check Engine Light illuminated
Rough idle or unstable engine speed
Reduced fuel economy and poor acceleration
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How Your ECU Detects This

Technical sensor logic and voltage thresholds

The ECU monitors the potentiometer voltage output from the left air intake servo motor to verify proper position feedback. The sensor should produce a variable voltage between 0.5V and 4.5V as the servo moves; a short to ground locks the signal at 0V, triggering a fault.

Voltage & Parameter Thresholds

ParameterNormal RangeFault Condition
Potentiometer Voltage 0.5V to 4.5V (variable) Below 0.2V (stuck at ground)
Sensor Resistance 1kΩ to 100kΩ (variable) Below 500Ω (short condition)
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Diagnostic & DIY Fix Guide

Check these in order — from cheapest to most complex
1
Wiring harness connector
Inspect and reseat the servo motor connector; clean corrosion from pins with contact cleaner.
2
Wiring loom and harness
Check the wiring between ECU and servo for cuts, pinches, or damaged insulation causing the short.
3
Servo motor potentiometer assembly
Replace the entire servo motor unit if continuity testing confirms internal short in the potentiometer.
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When to See a Professional Mechanic

Not all fault codes are safe to DIY

Code B1287 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 B1287

What happens after you fix the fault

Once the fault is repaired, B1287 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.