B1228

Code

Other B — Body

Fuel Temperature Sensor #2 Circuit Short to Battery

Brand: Other

Type: B — Body

Views: UK: 27 EN: 34 RU: 23

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Page language: EN

Causes

Damaged/chewed wiring harness with signal wire contacting B+
Corroded, bent or damaged sensor connector causing internal short to battery voltage
Failed fuel temperature sensor (internal short to battery)
Aftermarket or incorrect replacement sensor wired incorrectly
Faulty PCM/body control module or internal harness connector fault at the module
Recent work in the fuel rail area left a pinched or crimped wire making contact with a battery feed

Symptoms

MIL (Check Engine Light) illuminated
Stored B1228 DTC and possibly related DTCs
Incorrect fuel temperature reading in scan tool (extremely high or pegged value)
Possible driveability issues if fuel trim or injection timing uses fuel temp input
May fail emissions inspection due to wrong sensor data

What to check

Read DTCs and freeze-frame/fuel temperature data with a scan tool
Visually inspect sensor connector and wiring from the sensor to the harness for damage, corrosion, melting, pinched or exposed conductors
Check connector pins for B+ present on the signal terminal with connector disconnected (Key ON, engine OFF) — expect no battery voltage on signal
Backprobe signal wire with key ON and observe voltage on scan tool vs. multimeter
Measure sensor resistance (engine cold) with sensor disconnected — compare to manufacturer spec or typical NTC behavior (resistance decreases as temperature increases)
Check for continuity between the signal wire and battery positive (should be open) and for unintended continuity to ground

Signal parameters

Typical fuel temperature sensor type: NTC thermistor (resistance falls as temperature rises)
Expected idle/ambient: sensor output typically within ~0.2–4.8 V depending on design (value varies by vehicle)
Resistance ranges vary by design; common NTC sensors are roughly 1–100 kΩ across temperature extremes — consult OEM spec for exact values
When shorted to battery the signal voltage will be close to battery voltage (~12 V with engine off, ~13–14 V running) and scanner will show an abnormally high temperature or implausible reading

Diagnostic algorithm

Retrieve and record DTCs, freeze frame and live fuel temperature data with a scan tool. Note conditions when fault set.
Visually inspect the sensor, connector and wiring for damage, corrosion, loose pins or evidence of contact with a battery feed. Repair obvious damage.
With ignition OFF, disconnect the sensor connector. Inspect pins for corrosion or a pushed-out terminal that could contact B+. Clean or repair as needed.
With connector disconnected and Key ON (engine OFF), measure voltage between the sensor signal terminal and ground. Expected: no battery voltage on signal. If you see battery voltage, proceed to step 6.
With the sensor disconnected, check continuity between the signal wire and vehicle battery positive (B+). A short (low ohms) confirms wiring contacting B+. Also check for continuity to other fused B+ circuits that could be bridged.
Reconnect the harness to the sensor, backprobe the signal wire and measure voltage while monitoring live data. Compare to expected range and to battery voltage. If signal is near battery voltage only with harness connected, suspect sensor internal short.
Remove sensor and measure its resistance across terminals at ambient temperature and if available at different temperatures (warm/cold) to confirm thermistor behavior. Replace sensor if internal short or out-of-spec.
If wiring and sensor check good, inspect/repair harness all the way to the module and test for continuity to the PCM input. If wiring is good and issue persists, suspect PCM/input connector fault and consult manufacturer guidance before module replacement.
After repairs, clear codes, perform relearn if required, and verify with road test and scan tool that code does not return.
Safety note: avoid open flames and excessive heat near the fuel system when accessing sensors or fuel rail. Perform electrical tests with care to avoid shorting circuits.

Likely causes

Short in the sensor signal wire to battery (+) from wiring abrasion or chafing
Terminal pushed out of connector or bridged to a fused B+ terminal
Bad sensor with internal short to B+
Poor connector pin fit or corrosion allowing B+ to be applied to signal terminal
PCM input stage failure (less common)

Fault status

⚠️ Status

Fuel Temperature Sensor #2 circuit has detected a short to battery (high voltage) on the sensor signal circuit. The control module may ignore the input or use a fallback value, which can affect fuel control and emissions. Inspect wiring, connector, sensor and module input for faults.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0-2.5 hours