What Does P043C Mean?
The catalyst temperature sensor circuit on bank 2, sensor 2 (post-catalyst) is reading below the minimum voltage threshold. The signal is being pulled low, indicating a possible short to ground in the sensor, wiring, or connector. The PCM cannot accurately determine the post-catalyst exhaust temperature on bank 2. The MIL will be on but normal driving is unaffected.
Common Causes
35%
Internally shorted catalyst temperature sensor
30%
Signal wire shorted to ground from heat-damaged insulation near exhaust
18%
Corrosion in the connector causing signal bleed to ground
10%
Water intrusion in wiring or connector
7%
PCM internal pull-down fault on the sensor input
Diagnostic Steps
1
Verify the sensor signal reads below 0.2V on the scan tool or at the PCM connector with KOEO — this confirms the low circuit condition.
2
Disconnect the sensor and observe if the signal voltage rises toward 5V reference at the harness connector — if it rises, the sensor is shorted internally.
3
If the voltage stays low with the sensor disconnected, use an ohmmeter to check for continuity between the signal wire and chassis ground — any reading below 10K ohms indicates a wiring short to ground.
4
Visually inspect the wiring harness from the sensor location back toward the firewall, focusing on areas where the harness passes near exhaust components, sharp edges, or body seams.
5
Clean the sensor connector terminals with electrical contact cleaner and inspect for green corrosion or bent pins.
Estimated Repair Cost
$75 - $350
Parts + labor, varies by vehicle and location
The catalyst temperature sensor circuit on bank 2, sensor 2 (post-catalyst) is reading below the minimum voltage threshold. The signal is being pulled low, indicating a possible short to ground in the sensor, wiring, or connector. The PCM cannot accurately determine the post-catalyst exhaust tempera...
The most common cause of P043C (Catalyst Temperature Sensor Circuit Low (Bank 2 Sensor 2)) is: Internally shorted catalyst temperature sensor
Typical repair costs for P043C range from $75 to $350, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Safe to drive. Post-catalyst temperature monitoring is disabled, meaning a catalyst overheat condition would go undetected. Watch for unusual smells or excessive heat from the exhaust area.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P043C 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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