Catalyst Temperature Sensor Circuit Malfunction (Bank 2, Sensor 1)
P0435 indicates a malfunction in the catalyst temperature sensor circuit on Bank 2 (the side of the engine without cylinder #1). This sensor monitors exhaust temperature after the catalytic converter to ensure proper converter operation and emissions control. A circuit fault prevents the PCM from reading accurate temperature data.
What You Might Notice
- Check engine light illuminated
- Poor engine performance or hesitation
- Decreased fuel economy
- Increased emissions output
- Possible rough idle
Most Common Causes
- 1
Faulty catalyst temperature sensor
The sensor itself has failed electrically or mechanically, preventing accurate temperature readings from being sent to the PCM.
- 2
Wiring or connector issues
Corroded, loose, or damaged wiring and connectors in the sensor circuit prevent proper signal transmission between the sensor and PCM.
- 3
Exhaust air/fuel mixture imbalance
A lean or rich running condition causes abnormal exhaust temperatures that may trigger the sensor circuit fault as the PCM detects out-of-range values.
- 4
PCM or programming malfunction
A faulty powertrain control module or corrupted PCM programming may incorrectly interpret sensor signals or fail to communicate with the sensor circuit.
How to Diagnose It
- 1
Check Faulty catalyst temperature sensor — The sensor itself has failed electrically or mechanically, preventing accurate temperature readings from being sent to the PCM.
- 2
Check Wiring or connector issues — Corroded, loose, or damaged wiring and connectors in the sensor circuit prevent proper signal transmission between the sensor and PCM.
- 3
Check Exhaust air/fuel mixture imbalance — A lean or rich running condition causes abnormal exhaust temperatures that may trigger the sensor circuit fault as the PCM detects out-of-range values.
- 4
Check PCM or programming malfunction — A faulty powertrain control module or corrupted PCM programming may incorrectly interpret sensor signals or fail to communicate with the sensor circuit.
How to Fix It
- 1
Inspect and repair wiring/connectors
Locate the catalyst temperature sensor circuit on Bank 2, inspect all wiring for damage, corrosion, or loose connections. Clean corroded connectors with electrical contact cleaner and secure any loose connections.
- 2
Replace catalyst temperature sensor
If wiring is sound, remove the faulty catalyst temperature sensor from the exhaust manifold or catalytic converter and install a new sensor. Ensure proper torque and sealing.
- 3
Diagnose air/fuel mixture problems
Check for oxygen sensor faults, vacuum leaks, fuel injector issues, or fuel pressure problems that could cause an imbalanced air/fuel ratio. Use a scan tool to monitor fuel trim values.
- 4
PCM testing and reprogramming
If all sensors and wiring check out, have the PCM diagnosed by a specialist. The module may require reprogramming or replacement if corrupted.
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