Fuel Sender Circuit Open
The fuel gauge sender unit (a float inside your tank) has lost electrical connection to the dashboard. It's like a broken wire between your fuel tank and the gauge—the ECU can't read how much gas you have.
The ECU monitors the resistance signal from the fuel sender unit, which varies as the float rises and falls with fuel level. An open circuit (broken wire or failed sender) produces infinite resistance, which the ECU detects as an out-of-range signal. The module expects a specific resistance range; anything outside that triggers the fault.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| Fuel Sender Resistance | 30-240 ohms (full to empty) | >300 ohms or open circuit (infinite resistance) |
| Signal Voltage | 0.5-4.5 volts | No voltage or out-of-range signal detected |
Code B1202 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, B1202 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.