Cadillac Escalade T1XX (2021-Present) check engine light on but no codes

Symptoms

• Check engine light illuminated
• No DTCs found during OBD-II scan
• Possible rough idle
• Decreased fuel efficiency
• Engine hesitation during acceleration
• Unusual engine noises (e.g., knocking or pinging)

Diagnostic Steps

1. Inspect the gas cap for proper sealing and any signs of damage.
2. Check the battery voltage and connections to ensure proper electrical supply.
3. Inspect the engine for any vacuum leaks, particularly around hoses and intake manifold.
4. Verify the operation of the Mass Air Flow (MAF) sensor by performing a visual inspection and checking for dirt or obstructions.
5. Monitor live data from the engine control unit (ECU) using an OBD-II scanner to assess real-time sensor readings.
6. Look for any intermittent issues, such as wiring problems, that may not trigger a code but affect performance.

Solution

1. Preparation

• Gather required tools and ensure the vehicle is parked on a level surface.
• Disconnect the battery to ensure safety while working on electrical components.

2. Inspect the Gas Cap

• Remove the gas cap and inspect for cracks or wear; replace if damaged.
• Reinstall the gas cap securely and check for any signs of leakage around the seal.

3. Check Electrical Connections

• Using a multimeter, measure the battery voltage; it should be around 12.6 volts with the engine off.
• Inspect battery terminals; clean and tighten connections if corroded or loose.

4. Inspect for Vacuum Leaks

• Visually check all vacuum lines for cracks or disconnections.
• Use a smoke machine to detect any hidden leaks in the intake system.

5. Clean MAF Sensor

• Locate the MAF sensor; disconnect the wiring harness.
• Remove the sensor from the air intake (usually secured by screws or clips).
• Clean the MAF sensor with MAF cleaner spray and allow it to dry before reinstalling.

6. Update ECU Software

• Connect an authorized scan tool to access the ECU.
• Check for any software updates from the manufacturer and apply if available.