Catalyst Temperature Sensor Circuit Low (Bank 1 Sensor 2)
The P042C code indicates that the powertrain control module (PCM) has detected a low voltage signal from the catalyst temperature sensor located downstream of the catalytic converter on bank 1. This sensor monitors the temperature of the catalytic converter to ensure efficient operation and emissions control. A low circuit condition typically means the sensor signal is below the expected range, which can be caused by a faulty sensor, wiring issues, or a problem with the PCM. This code may lead to reduced catalytic converter efficiency and increased emissions.
01. Most Common Causes
- Faulty catalyst temperature sensor
- Open or shorted wiring in the sensor circuit
- Poor electrical connection at the sensor connector
- Failed PCM (rare)
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Possible decrease in fuel economy
- Failed emissions test
- Possible catalytic converter damage if ignored
03. Step-by-Step Diagnosis
Step 1: Use an OBD2 scanner to confirm the code and check for other related codes.
Step 2: Visually inspect the catalyst temperature sensor and its wiring for damage, corrosion, or loose connections.
Step 3: Test the sensor's resistance and voltage output with a multimeter and compare to manufacturer specifications.
Step 4: If sensor and wiring are okay, check for PCM issues or perform a more advanced diagnostic scan.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
You can drive short distances, but it's not recommended for extended periods as it can lead to catalytic converter damage and increased emissions.
How much does it cost to fix?▼
The cost typically ranges from $50 to $150 for a new sensor, plus labor if you have it installed by a mechanic.