B1227

Code

Other B — Body

Fuel Temperature Sensor #2 Circuit Open

Brand: Other

Type: B — Body

Views: UK: 21 EN: 46 RU: 42

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Page language: EN

Causes

Broken or disconnected sensor wiring (open circuit)
Corroded, bent, or pushed-out connector pins
Failed fuel temperature sensor (thermistor open)
Poor ground or missing reference voltage from PCM
Damage from fuel exposure or mechanical abrasion
PCM input circuit fault (less common)

Symptoms

Malfunction Indicator Lamp (MIL) / Check Engine light on
Possible hard cold start, drivability issues or rough idle
Reduced fuel economy or incorrect fuel trim during warm-up
Fuel system may run in default mode for fuel temperature input

What to check

Read DTC(s) and freeze frame / live data with scan tool; note conditions when code set
Visually inspect sensor, wiring harness and connector for damage, corrosion or fuel intrusion
Backprobe sensor connector with key ON and measure signal voltage and reference voltage
Measure sensor resistance (with sensor disconnected) and compare to expected thermistor behaviour (resistance falls as temperature rises)
Perform continuity check between sensor connector and PCM pin; check for short to battery or ground
Wiggle test wiring while monitoring live data for intermittent opens

Signal parameters

Sensor type: typically NTC thermistor mounted in fuel rail or supply line (resistance decreases as temperature rises)
Reference voltage: commonly a 5 V reference from PCM (verify on vehicle)
Normal signal voltage range: typically within 0.2–4.8 V depending on fuel temperature (vehicle-specific)
Open-circuit symptom: very high signal voltage or 'OL' resistance reported to PCM
Short-to-ground symptom: very low signal voltage or near 0 V

Diagnostic algorithm

Connect a scan tool, read and record DTC(s) and freeze-frame data. Confirm B1227 is active or stored.
Visually inspect the sensor and harness for obvious damage, fuel contamination or pin corrosion at the connector and PCM.
With ignition ON (engine off), backprobe the sensor connector: verify PCM reference voltage (typically ~5 V) and good ground. If reference is missing, trace to PCM fuse/fueling modules.
Measure the sensor signal voltage while changing fuel temperature if practical (or compare to known good sensor/data). An open circuit usually results in a high signal voltage or no changing value.
Disconnect sensor and measure resistance across sensor terminals with a multimeter. Confirm resistance changes with temperature (or shows open/infinite if failed).
Check continuity between the sensor connector and the PCM pin. Repair any open or high-resistance sections of wiring. Repair corroded pins or replace connector as needed.
After repairs or sensor replacement, clear codes and perform a test drive or reproduce the original conditions to confirm the code does not return.
If wiring and sensor check good but code persists, consider PCM input circuit testing or replacement per vehicle manufacturer procedures.

Likely causes

Open or damaged harness between sensor and PCM
Corroded/poor connector contact at sensor or harness
Failed fuel temperature sensor
Intermittent open caused by vibration or pin damage

Fault status

⚠️ Status

B1227 — Fuel Temperature Sensor #2 Circuit Open. PCM detected an open or nonexistent signal from the fuel temperature sensor #2 circuit; check sensor, connector, wiring and PCM reference/ground.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-2.0 hours