Easy one-page printout for the garage or repair shop
This summary uses the existing diagnostic information shown in full below.
This code means that the car's computer thinks the temperature of the exhaust gases is not normal. It's like when you have a thermometer and it shows a temperature that doesn't make sense.
This code is triggered when the exhaust gas temperature sensor on bank 1, sensor 1, reports a temperature that is outside the expected range.
The P2478 code indicates that the exhaust gas temperature sensor located on bank 1, sensor 1, is reporting a temperature that is either too high or too low compared to the expected values. This sensor is crucial for monitoring and controlling the emissions system, and an out-of-range reading can affect engine performance and emissions control.
• Check Engine Light illuminated
• Poor fuel economy
• Reduced engine performance
• Faulty exhaust gas temperature sensor
• Wiring issues or poor electrical connections
• Exhaust leaks or blockages
Exhaust Gas Temperature Sensor: A sensor that measures the temperature of the exhaust gases.
Bank 1: The side of the engine where cylinder 1 is located.
• Use an OBD-II scanner to confirm the P2478 code is present.
• Inspect the exhaust gas temperature sensor and wiring for damage.
• Test the sensor's resistance and compare it to specifications.
• Replace the faulty exhaust gas temperature sensor.
• Repair or replace damaged wiring or connectors.
• Fix any exhaust leaks or blockages.
• OBD-II scanner
• Multimeter
• Wrench set
$150 - $300
Moderate
• Ford F-150
• Chevrolet Silverado
• Toyota Camry
• Regularly inspect and maintain the exhaust system.
• Ensure proper sensor installation and connections.
• Use high-quality fuel to reduce deposits.
Sensor Issue
• Have the vehicle inspected by a professional mechanic.
• Avoid driving the vehicle if performance issues are severe.
• Regularly check for exhaust system maintenance.
Check with your vehicle manufacturer for warranty coverage on emissions-related components.
This code has been known to appear in vehicles with high mileage or those with poor maintenance records.
Moderate – While the vehicle can still be driven, it should be repaired soon to avoid further damage.
Driving with a malfunctioning emissions system may violate emissions regulations and contribute to environmental pollution.
• Engine at operating temperature
• Vehicle in a safe, stationary position
The exhaust gas temperature sensor is located in the exhaust system, usually near the exhaust manifold or turbocharger on bank 1.
Q: What happens if I ignore the P2478 code?
A: Ignoring this code can lead to increased emissions, poor fuel economy, and potential damage to the catalytic converter.
Q: Can I drive my car with a P2478 code?
A: While you can drive with this code, it's not recommended for long periods as it may lead to further issues.
High-End · Full-system diagnostics
A full-system bidirectional platform aimed at advanced DIY users and professional diagnostic workflows.
Network faults often require full-system access instead of a generic code reader alone.
View on Amazon
Universal · Digital multimeter
A solid entry-level multimeter for voltage, continuity, resistance, and basic electrical troubleshooting.
Helpful for checking voltage drops, grounds, and basic circuit health when modules are not communicating.
View on Amazon
Universal · Wire connectors and repair kit
Useful when diagnosis points toward damaged wiring, corroded terminals, or connector repairs.
Useful if diagnosis points toward damaged connectors, wiring, or terminal repairs.
View on AmazonThese are optional diagnostic tools, not guaranteed fixes. As an Amazon Associate I earn from qualifying purchases.