B1298

Code

ALFA ROMEO B — Body

Volumetric anti-theft sensor supply short to positive

Brand: ALFA ROMEO

Type: B — Body

Views: UK: 7 EN: 7 RU: 6

AI status

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Page language: EN

Read and record all related codes with a scan tool, note freeze-frame or related events
Inspect wiring harness from volumetric sensor to body control module for damage, chafe points and repairs
Visually inspect sensor connector for corrosion, bent pins, melting or water ingress
Check fuses and fusible links for the anti-theft circuit (replace only after fault cleared)
Measure supply voltage at sensor connector with ignition ON and engine OFF using a digital multimeter
Disconnect volumetric sensor and see if code clears or if short persists (watch for other modules that share feed)

Normal supply voltage at sensor with ignition ON: ~11–14 V (battery voltage)
When ignition OFF supply should be 0 V if feed is switched off (some vehicles provide constant 12V; verify with wiring diagram)
Expected resistance: wiring supply conductor to battery positive should show low resistance (typically
No voltage drop or spiking when connectors are moved; no short to battery positive at sensor pin when sensor is disconnected (unless feed is constant positive per design)

Retrieve freeze frame and all stored codes; note whether supply is described as short to positive specifically and whether feed is constant or switched.
Obtain wiring diagram and identify sensor supply pin, ground and any fused/shared feeds or accessory connections.
Visually inspect sensor and harness for damage, corrosion or aftermarket taps; repair obvious damage.
With ignition ON, measure voltage at sensor supply pin; compare to battery voltage and to wiring diagram expected state (switched/constant).
With sensor connector disconnected, measure for short: check for battery positive present at the supply pin when no supply should be present. If positive exists unexpectedly, trace back toward fuse/BCM.
If short is present only with connector connected, suspect sensor internal short—replace sensor and re-test.
If short is present with connector disconnected, isolate by disconnecting intermediate connectors and measuring; use backprobe and continuity checks to find the chafe/short location.
Repair or replace damaged wiring, connectors or sensor. If wiring repair is performed, protect with loom and grommets to prevent re-chafe.
After repair, clear codes, perform full system test (arm/disarm, verify sensor function) and confirm no reoccurrence. If fault persists and wiring/sensor good, consider BCM/anti-theft module diagnosis or replacement with dealer-level diagnostics.

Short in the sensor supply wire (chafed against chassis or another positive conductor)
Volumetric sensor internal failure creating a direct short to the supply rail
Connector contamination/corrosion causing conductive path to positive

⚠️ Status

Volumetric anti-theft sensor supply shorted to positive (B1298) — check sensor, wiring and connectors for short to battery positive.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0-2.5 hours

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