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Code P1490

Symptoms

• Check Engine Light is on

• Poor fuel economy

• Reduced engine performance

Common Causes

• Faulty Exhaust Gas Temperature Sensor

• Wiring issues such as shorts or open circuits

• Corroded or damaged connectors

Glossary

Exhaust Gas Temperature Sensor: A sensor that measures the temperature of the exhaust gases.

ECM: Engine Control Module, the computer that controls engine functions.

Related Codes

• P0544

• P2031

Official description

Exhaust Gas Temperature Sensor 'A' Electrical

Laymans terms

This code means there's a problem with a sensor in the car that checks how hot the exhaust is. It's like a thermometer for the car's exhaust, and it's not working right.

Explanation

The P1490 code indicates an electrical issue with the Exhaust Gas Temperature (EGT) Sensor 'A'. This sensor measures the temperature of the exhaust gases to ensure the engine is running efficiently and to protect components from overheating.

Technical description

The Exhaust Gas Temperature Sensor 'A' is responsible for measuring the temperature of the exhaust gases leaving the engine. This information is used by the engine control module (ECM) to adjust fuel injection and timing. An electrical problem with this sensor can cause incorrect temperature readings, affecting engine performance and emissions.

Diagnosis steps

• Use an OBD-II scanner to confirm the code

• Inspect the wiring and connectors for damage or corrosion

• Test the Exhaust Gas Temperature Sensor with a multimeter

Repair procedures

• Replace the faulty Exhaust Gas Temperature Sensor

• Repair or replace damaged wiring or connectors

• Clear the code and test drive the vehicle to ensure the issue is resolved

Tools required

• OBD-II scanner

• Multimeter

• Basic hand tools

Estimated repair cost

$100 - $300

Difficulty level

Moderate

Commonly affected vehicles

• Volkswagen Jetta

• Audi A4

• BMW 3 Series

Preventive measures

• Regularly inspect and maintain the exhaust system

• Ensure sensors are clean and free from debris

• Check wiring and connectors for wear and tear

Error code type

Sensor Issue

User experience recommendations

• Have the vehicle inspected by a professional if the Check Engine Light is on

• Avoid prolonged driving with this code active to prevent further damage

Warranty information

Check with the vehicle manufacturer for warranty coverage on emissions-related components.

Historical data

This code has been associated with issues in vehicles with advanced emissions control systems, particularly in diesel engines.

Urgency level

Moderate – It should be addressed soon to prevent potential damage to the exhaust system and ensure optimal engine performance.

Legal and safety notice

Driving with a malfunctioning exhaust gas temperature sensor may lead to increased emissions, which can be illegal in some areas.

Testing conditions

• Engine at operating temperature

• Vehicle stationary with engine idling

Component location

The Exhaust Gas Temperature Sensor 'A' is typically located in the exhaust manifold or downpipe, near the turbocharger if equipped.

FAQs

Q: Can I drive with a P1490 code?
A: It's not recommended to drive for extended periods with this code active, as it can lead to further engine or exhaust system issues.

Q: How do I reset the Check Engine Light after repair?
A: Use an OBD-II scanner to clear the code after the repair is completed.

Last updated: Apr 16, 2026 • Source: internal database
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