Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSCHEVROLET1999PICKUP C2500, 2D PICKUP, 6.5 F, STANDARDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 239 (ENGINE CONTROLS - TROUBLE SHOOTING - NO CODES - 3.4L)SYMPTOMSPOOR FUEL ECONOMYSENSOR/SYSTEM
1999 Chevrolet Pickup C2500, 2D Pickup, 6.5 F, Standard
Poor Fuel Economy: Sensor/System
1999 Chevrolet Pickup C2500, 2D Pickup, 6.5 F, StandardSECTION Sensor/System
WARNING: This page is about a different car, the 2003 Pontiac Grand Am, 2003 Oldsmobile Alero, 2003 Chevrolet Monte Carlo, and 2003 Chevrolet Impala. However, it is still accessible from the selected car via links, so may be relevant.
- Observe the 24X crank sensor and the CMP sensor signal present parameters on the scan tool. If both are not responding, inspect the sensor feed circuit. Both sensors use a common feed circuit.
- Inspect the air intake ducts for being collapsed, damaged areas, looseness, improper installation, or leaking, especially between the Mass Airflow (MAF) sensor and the throttle body.
- Inspect for proper operation of the speedometer. Go to appropriate ANALOG INSTRUMENT PANELS article in ACCESSORIES & EQUIPMENT.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.