Fuel Temperature Sensor #1 Circuit Failure
Your vehicle's fuel temperature sensor isn't communicating properly with the engine computer, similar to a thermometer that's broken or unplugged. The ECU can't read how hot the fuel is, which affects fuel injection timing and engine performance.
The ECU monitors the fuel temperature sensor's voltage output to adjust fuel density calculations and injection parameters. The sensor should produce a variable voltage between 0.5V and 4.5V as fuel temperature changes from cold to hot. If the signal is absent, shorted, or out of range, the ECU sets this fault code.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| Sensor Voltage | 0.5V to 4.5V (varies with temperature) | Below 0.1V or above 4.8V; no signal detected |
| Fuel Temperature Range | -40°C to 125°C | Signal implausible or circuit open/shorted |
Code B1222 is a low-severity fault. Your vehicle is generally safe to drive to a workshop for diagnosis. However, do not ignore it indefinitely — low-severity codes often indicate developing problems that become expensive if neglected. Book a diagnostic appointment within 2–4 weeks. If you notice any additional symptoms (rough running, power loss, unusual smells), treat it as higher priority.
Once the fault is repaired, B1222 can be cleared using any OBD-II scanner. Connect the scanner, navigate to "Clear Codes" or "Erase DTCs," and confirm. The check engine light turns off immediately.
The code will return if the root cause was not actually fixed. The ECM re-detects the fault within 1–3 drive cycles and sets the code again.