Exhaust Gas Temperature Sensor Circuit Low (Bank 1 Sensor 1)
The P0545 code indicates that the exhaust gas temperature (EGT) sensor on Bank 1, Sensor 1 (pre-catalyst) is reporting a voltage lower than the expected range. This sensor monitors exhaust temperature to protect the catalytic converter and optimize engine performance. A low circuit condition typically means the sensor signal is shorted to ground, the sensor is internally shorted, or the wiring has a fault. This can lead to incorrect fuel mixture adjustments and potential catalyst damage.
1. Most Common Causes
- Short to ground in the EGTS sensor wiring
- Short circuit between the signal and ground wires of the sensor
- Exhaust gas temperature sensor internally damaged or with out-of-spec resistance
- Sensor connector corroded, oxidized, or contaminated with moisture
- Wiring damaged by excessive heat in the exhaust area
- Internal ECM/PCM failure (less common)
- Damaged pull-up resistor in the reference circuit
2. Symptoms You Will Notice
- Check Engine Light illuminated
- Reduced fuel economy
- Possible limp mode or reduced engine power
- Failed emissions test
3. Step-by-Step Diagnosis
Step 1: Use an OBD2 scanner to confirm code P0545 and check for other codes.
Step 2: Visually inspect the EGT sensor and wiring for damage, corrosion, or loose connections.
Step 3: Disconnect the sensor and measure resistance; compare to manufacturer specs (typically 10-200 ohms at room temperature).
Step 4: Check for short to ground by measuring resistance between sensor signal wire and ground; should be infinite.
Step 5: If sensor and wiring are okay, test the ECM output by backprobing the signal wire with ignition on; should see a voltage (usually 5V reference).
Step 6: Replace the EGT sensor if faulty; clear codes and test drive.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended to drive long distances. The ECM may use incorrect fuel trims, potentially damaging the catalytic converter. Short trips to a repair shop are okay.
How much does it cost to fix?▼
Typically $50-$150 for parts and labor. The sensor itself costs $20-$80, and labor is about $30-$70.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.