Code
B1307
ALFA ROMEO
B — Body
Oil level switch short to positive
Views:
UK: 4
EN: 11
RU: 5
AI status
Completed
Completed
100%
Causes
- Damaged or chafed wiring causing contact with battery positive or fused power feed
- Corroded, bent or contaminated connector pins at the oil level switch
- Internal short inside the oil level switch (sensor)
- Aftermarket accessory or recent repair left a splice/bridge to B+
- Faulty body control module / instrument cluster input (less common)
- Blown or incorrect fuse providing power to the circuit
Symptoms
- Oil level warning lamp or message illuminated
- Oil level indicator reading incorrectly (e.g., stuck or always ‘full’)
- Associated engine or start/stop functions inhibited in some models
- Intermittent or permanent fault stored in vehicle fault memory
What to check
- Read and record freeze frame/fault details with a diagnostic scanner; clear and see if code returns
- Visual inspection of wiring harness and connector at the oil level switch: look for chafing, heat damage, or repairs
- Inspect connector for corrosion, bent pins, or water ingress
- Check related fuses and fused power feeds for correct value and condition
- Backprobe the sensor signal pin with ignition ON and measure voltage with a DMM
- Disconnect the oil level switch connector and re-scan - note if the code changes or clears
Signal parameters
- When shorted to positive: signal ≈ battery voltage (typically ~12–14V with ignition ON)
- Normal oil level switch signal: either high-impedance/open or pulled to ground depending on design (often near 0V when activated)
- When sensor disconnected: signal should not be solid battery voltage; presence of B+ indicates a short or incorrect feed
Diagnostic algorithm
- Connect a diagnostic scan tool, read DTC B1307 and freeze-frame data; clear the code and perform an ignition cycle to see if it returns.
- Visually inspect the oil level sensor connector and harness routing for damage, corrosion or signs of repair. Pay attention where harness passes near metal edges, engine mounts, or exhaust.
- With ignition ON (engine off), backprobe the signal wire at the oil level switch connector. Measure DC voltage to ground. If ~12V is present, suspect a short to positive upstream.
- Disconnect the oil level switch connector. If code clears or measured voltage disappears, suspect the sensor or connector as the fault. If voltage remains, trace the harness toward the BCM/power distribution to find a splice or short to B+.
- Check continuity between the signal wire and battery positive (with key off). A direct short (near zero ohms) indicates wiring short. Also check continuity to ground where appropriate per vehicle wiring diagram.
- If wiring checks are good, test or replace the oil level switch per factory procedure. After replacement, clear codes and re-test for proper operation.
- If the fault persists after sensor replacement and harness repair, inspect body control module / instrument cluster inputs and grounds; consult wiring diagrams and consider module bench testing or replacement as last resort.
Likely causes
- Wiring harness damaged near the oil pan or routing points
- Connector corrosion allowing positive voltage to feed the signal pin
- Failed oil level sensor with internal short to positive
Fault status
Status
Oil level switch circuit has a short to battery positive; the control module detects unexpected voltage on the oil level input.
Repair difficulty: Medium
Diagnostic time: 0.5 - 2.0 hours
Similar codes
Your experience will help others
+100 karma for a short comment :)
Was this AI description helpful?
Your feedback helps improve AI descriptions.
👍 Like
0
👎 Dislike
0
Send to email