Catalyst Temperature Sensor High Input (Bank 1)
The exhaust temperature sensor after your catalytic converter is reading hotter than normal, like a thermometer stuck on high. This could mean the sensor is failing, the converter is overheating, or there's an electrical wiring issue.
The ECU monitors voltage output from the catalyst temperature sensor (usually a thermocouple or resistance-based sensor) located downstream of Bank 1's catalytic converter. It compares the signal voltage against expected temperature ranges; when voltage exceeds the high threshold, it indicates either abnormally high exhaust temps or sensor malfunction.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| Sensor Voltage Output | 0.2-0.8V (typically 200-800°C equivalent) | >0.9V or sustained high signal |
| Exhaust Temperature | 400-600°C under load | >800°C or rapid spikes |
Code P0430 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, P0430 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.