What Does P0435 Mean?
The PCM has detected a general malfunction in the catalyst temperature sensor circuit on bank 2, sensor 1 (upstream of or at the catalytic converter). The signal may be erratic, missing, or outside the normal operating range. This sensor monitors catalyst temperature to verify proper operation and protect against overheating. The driver may not notice driveability symptoms but the MIL will illuminate.
Common Causes
35%
Failed catalyst temperature sensor (internal failure or drift)
30%
Damaged wiring or connector between the sensor and PCM
15%
Corrosion or water intrusion at the sensor connector
12%
Poor sensor ground connection causing erratic readings
8%
PCM internal circuit fault on the sensor input
Diagnostic Steps
1
Monitor the catalyst temperature sensor PID on the scan tool — compare the reading to the engine coolant temperature on a cold start. Both should read approximately the same ambient/coolant temperature before the engine is started.
2
Backprobe the sensor signal wire and verify voltage is within the expected 0.5–4.5V range. Erratic voltage or a flat-lined signal indicates a circuit issue.
3
Disconnect the sensor and measure its resistance — compare to the manufacturer's resistance-temperature chart. A typical thermistor-type sensor should read 2000–3000 ohms at room temperature.
4
Inspect the connector and wiring for heat damage, corrosion, or melted insulation — this sensor is located in the exhaust stream where temperatures routinely exceed 1000°F.
5
Verify the 5V reference and ground circuits at the sensor connector are present and within specification.
Estimated Repair Cost
$100 - $400
Parts + labor, varies by vehicle and location
The PCM has detected a general malfunction in the catalyst temperature sensor circuit on bank 2, sensor 1 (upstream of or at the catalytic converter). The signal may be erratic, missing, or outside the normal operating range. This sensor monitors catalyst temperature to verify proper operation and p...
The most common cause of P0435 (Catalyst Temperature Sensor Circuit Malfunction (Bank 2, Sensor 1)) is: Failed catalyst temperature sensor (internal failure or drift)
Typical repair costs for P0435 range from $100 to $400, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Safe to drive. Without accurate catalyst temperature monitoring, the PCM cannot detect a potentially overheating catalyst. If you notice a sulfur smell or see the exhaust system glowing, stop driving immediately.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P0435 to identify the root cause.
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Quick Info
Category
Powertrain
System
Exhaust / Catalytic Converter
Difficulty
Type
Generic (SAE)
Recommended Tools
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