B1338

Door Ajar RR Circuit Short To Ground

Body Chassis/Safety Door sensors 🟢 Low — Fix at next service ✅ Safe to Drive
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What This Actually Means

In plain language — no jargon

The rear right door ajar sensor circuit is shorted to ground, meaning the electrical signal wire is touching the metal chassis instead of properly communicating the door position. It's like a light switch stuck in the 'on' position because the wire got pinched.

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Symptoms You May Notice

3 known symptoms for this code
Door ajar warning light stays illuminated on dashboard
Interior dome light remains on continuously
Vehicle may not lock doors or triggers false alarm warnings
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How Your ECU Detects This

Technical sensor logic and voltage thresholds

The ECU monitors the voltage signal from the rear right door ajar switch, expecting a high voltage when the door is closed and low voltage when open. A short to ground forces the signal to zero volts constantly, causing the ECU to think the door is always in an abnormal state.

Voltage & Parameter Thresholds

ParameterNormal RangeFault Condition
Door Ajar Switch Signal Voltage High (4.5-5.5V) when closed, Low (0.5V) when open Continuous 0V (shorted to ground)
Circuit Resistance 500-1000 ohms normal, infinite when open Less than 50 ohms (direct short)
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Diagnostic & DIY Fix Guide

Check these in order — from cheapest to most complex
1
Door ajar switch connector
Inspect the RR door jamb switch connector for corrosion, moisture, or loose pins and reseat or clean the connection.
2
Door ajar switch wiring harness
Check the wiring between the door and frame for pinches, cuts, or abrasion where insulation is compromised.
3
Door ajar switch assembly
Replace the rear right door jamb switch if corrosion or internal failure is confirmed.
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When to See a Professional Mechanic

Not all fault codes are safe to DIY

Code B1338 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 B1338

What happens after you fix the fault

Once the fault is repaired, B1338 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.