P0171
System Too Lean
Description
System too Lean (Bank 1) This body system diagnostic trouble code indicates an issue with the vehicle's comfort, safety, or convenience systems.
OBD Codes Details
Possible Causes
Blown fuse, faulty switch, damaged wiring harness, poor electrical connection
Solution
Check fuses and relays, inspect wiring harness, test switches and sensors, repair damaged circuits
Symptoms
- Engine runs lean causing rough idle
- Engine may hesitate or stumble during acceleration
- Increased engine temperature
- Poor fuel economy
- Engine pinging or knocking sounds
Diagnostic Recommendations
- Check for vacuum leaks in intake manifold and hoses
- Test Mass Air Flow (MAF) sensor operation and cleanliness
- Inspect fuel pressure and fuel pump performance
- Check oxygen sensor readings and response time
- Examine PCV system for proper operation
- Test fuel injectors for proper flow and spray pattern
Repair Cost Estimate
- Vacuum leak repair: $100-300
- MAF sensor cleaning/replacement: $50-400
- Fuel pump replacement: $400-800
- Oxygen sensor replacement: $200-500
- Total diagnostic and repair: $200-1500
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Fact-checking completed
Verified by:
Pavel Volkov
Created:
Last updated:
Information verified against official sources
Official Sources
Society of Automotive Engineers
Official OBD-II diagnostic trouble codes standard (SAE J2012)
Automotive engineering standards organization
International Organization for Standardization
International standard for vehicle diagnostic systems
International standards for automotive diagnostics
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