Failed catalyst temperature sensor (bank 2 sensor 2); Open or shorted wiring in the sensor circuit; Corroded or loose electrical connector at the sensor; Damaged sensor pigtail or harness near the exhaust; Poor ground connection for the sensor circuit; Faulty engine control module (ECM) driver circuit, though uncommon

DTC codes / P04xx · Auxiliary emission controls / P043C

P043CCatalyst Temperature Sensor Circuit Low Bank 2 Sensor 2

Q: What does code P043C mean?

Catalyst Temperature Sensor Circuit Low Bank 2 Sensor 2. P043C means the engine computer has detected a low signal voltage from the catalyst temperature sensor located after the bank 2 catalytic converter. The sensor's output is lower than the expected range for the current operating conditions, indicating an open circuit, short to ground, or a sensor that has failed.

P043C means the engine computer has detected a low signal voltage from the catalyst temperature sensor located after the bank 2 catalytic converter. The sensor's output is lower than the expected range for the current operating conditions, indicating an open circuit, short to ground, or a sensor that has failed.

SystemPowertrain

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyIntermediate

AreaAuxiliary emission controls

Symptoms you may notice

Illumination of the check engine light, often with no other symptoms
Reduced engine performance or power in some cases
Slightly lower fuel economy if the computer enters a default strategy
In rare cases, a noticeable sulfur or rotten egg smell from the exhaust
No drivability complaints at all on many vehicles

Common causes, most likely first

Failed catalyst temperature sensor (bank 2 sensor 2)
Open or shorted wiring in the sensor circuit
Corroded or loose electrical connector at the sensor
Damaged sensor pigtail or harness near the exhaust
Poor ground connection for the sensor circuit
Faulty engine control module (ECM) driver circuit, though uncommon

How to diagnose and fix it

Inspect the sensor connector and wiring for damage, corrosion, or looseness
Measure sensor resistance and compare to the manufacturer's specification
Check for reference voltage and ground at the sensor connector with the key on
Perform a voltage drop test on the ground circuit to rule out high resistance
Replace the catalyst temperature sensor if it fails electrical tests
Repair or replace damaged wiring and clear the code
Verify the repair by completing a drive cycle and confirming the code does not return

What a low catalyst sensor signal really means

A low signal code often results from a sensor that has drifted out of range rather than a completely dead sensor, so resistance testing at operating temperature is critical.
Exhaust leaks upstream of the sensor can cause temperature fluctuations that mimic a low signal, so inspect the exhaust system before condemning the sensor.
The catalyst temperature sensor is used to protect the converter from overheating, and a false low reading may cause the computer to alter fuel control, affecting emissions.
On some vehicles, a low signal from this sensor can be caused by a short to ground in the wiring harness where it rubs against the chassis or exhaust shield.
Do not replace the catalytic converter based on this code alone; the sensor circuit is the primary suspect and should be ruled out first.

Can I keep driving with P043C?

You can generally continue driving with this code, but avoid heavy loads and sustained high speeds until it is repaired, as the computer may not properly protect the catalytic converter from overheating. Have the fault diagnosed soon to prevent potential emissions system damage.

Tools that help

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Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.