P0430
Catalyst Temperature Sensor High Input (Bank 1)
Powertrain Emission Controls Catalyst monitoring 🟡 Moderate — Fix within a week
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What This Actually Means
In plain language — no jargon

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.

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Symptoms You May Notice
3 known symptoms for this code
Check Engine Light illuminated
Reduced fuel economy and power loss
Rotten egg smell from exhaust
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Embedded Systems Insight
What the ECU/ECM is actually computing

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.

Voltage & Parameter Thresholds

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
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Diagnostic & DIY Fix Guide
Check these in order — from cheapest to most complex
1
Wiring harness and connectors
Inspect the sensor connector and wiring for corrosion, loose terminals, or damaged insulation; clean or reseat connections.
2
Catalyst temperature sensor
Replace the faulty sensor with an OEM or equivalent unit if voltage readings remain high after connector inspection.
3
Catalytic converter
If sensor is good but temps stay high, the converter may be clogged or failing; have it tested or replaced by a technician.