Code
B1296
ALFA ROMEO
B — Body
Electrical supply sensor circuit
Views:
UK: 5
EN: 6
RU: 8
AI status
Completed
Completed
100%
Causes
- Open or shorted wiring between sensor and control module
- Corroded, loose or damaged sensor connector
- Blown fuse or faulty supply/relay for the sensor circuit
- Failed or degraded sensor element
- Poor ground/earth connection or body chassis corrosion
- Intermittent fault from water ingress or connector contamination
Symptoms
- Related subsystem degraded or inoperative (depends on sensor function)
- Warning or advisory message on dash; possible instrument cluster anomalies
- Intermittent faults that may clear and return
- Possible battery/charging warning if supply monitoring relates to battery circuit
- No-start not typical for body sensor faults but may occur if function is inhibited
What to check
- Read stored freeze-frame data and full module fault history with a compatible scanner
- Perform a visual inspection of wiring, connectors and sensor for damage, corrosion and water ingress
- Check relevant fuses and relays for continuity and correct operation
- Backprobe sensor connector and measure supply voltage, reference voltage and signal while ignition ON and during function
- Check continuity and resistance to ground for sensor ground circuit
- Perform wiggle test on harness while monitoring signal to reproduce intermittent faults
Signal parameters
- Supply voltage at sensor connector (ignition ON): battery voltage ≈ 11–14.5 V
- Reference voltage (if applicable): approx. 5.0 V ±0.2 V
- Sensor signal voltage: expected 0–5 V depending on sensor type; should not be shorted to 0 V or battery voltage
- Connector resistance: open circuit = infinite; typical continuity to ECU < 5 ohms for power/ground conductors
- Insulation resistance: no short to chassis (megohm range preferred)
Diagnostic algorithm
- Retrieve fault details (freeze frame, event count) with OEM-compatible scan tool and note conditions when fault set.
- Visually inspect sensor, connector and harness for corrosion, damage, water ingress and secure mounting.
- Verify fuses and relays for the circuit; replace if blown and retest.
- Measure supply voltage at sensor connector with ignition ON; confirm battery voltage present and stable.
- Measure any reference voltage (typically ~5 V) and signal output while operating the relevant system. Compare to expected ranges.
- Check ground continuity from sensor ground pin to chassis and to control module ground; repair poor grounds.
- Perform continuity/resistance checks between sensor connector and control module pins to detect opens or high resistance.
- If wiring and power/ground are correct but signal is out-of-range, disconnect sensor and measure expected internal resistance or bench-test sensor per OEM spec; replace sensor if failed.
- If after sensor replacement the fault persists, inspect/repair wiring near ECU and consider module input circuit fault — consult wiring diagram and test module drivers.
- Clear codes and perform functional test/road test to confirm repair; monitor for return of code and verify no other dependent faults are present.
Likely causes
- Loose or corroded connector at the sensor
- Open/short in harness (rodent damage, chafing)
- Blown fuse or faulty supply relay feeding the sensor
- Failed sensor (internal electronics)
- Bad ground/earth strap or mounting point
Fault status
Status
Stored when the control module detects an abnormal condition in the electrical supply or signal circuit for a monitored sensor (open, short, intermittent or out-of-range).
Repair difficulty: Medium
Diagnostic time: 0.5-2.0 hours
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