Heated Oxygen Sensor (H02S) Heater Control Circuit Bank 1 Sensor 1
The oxygen sensor heater on bank 1, sensor 1 isn't warming up properly, like a light bulb that won't turn on. Your engine can't get accurate fuel readings without it being hot enough to work.
The ECM sends a control voltage to heat the O2 sensor to its operating temperature (around 600°C). It monitors the heater circuit current draw and response time. If voltage, current, or temperature feedback is out of range, the fault sets.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| Heater Circuit Voltage | 12V supply when commanded | Below 10V or no voltage detected |
| Heater Response Time | Sensor ready within 10-15 seconds | Sensor not reaching operating temp or excessive delay |
Code P0030 is a moderate fault. You can generally drive to a workshop, but avoid long trips or high-load driving (motorway, uphill towing) until it is diagnosed. If the code keeps returning after clearing, or if you notice the symptoms listed above worsening, do not delay professional diagnosis. Many moderate codes have multiple possible root causes — a mechanic with live OBD data can identify the exact fault more efficiently than part-by-part trial and error.
Once the fault is repaired, P0030 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.