P0172
Medium SeveritySystem Too Rich (Bank 1)
Fuel System
What Does P0172 Mean?
Bank 1 is running rich — too much fuel relative to air. The ECM cannot trim enough fuel out to compensate.
Common Fix
Replace leaking injector or fuel pressure regulator
Estimated Cost (DIY)
$30 - $200
Symptoms
- ⚠️Black exhaust smoke
- ⚠️Strong fuel smell
- ⚠️Poor fuel economy
- ⚠️Fouled spark plugs
Common Causes
How to Diagnose P0172
- 1Check fuel pressure
- 2Inspect fuel injectors for leaks
- 3Check O2 sensor operation
- 4Inspect air filter
OEM Diagnostic Flowchart
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Related Resources
Repair guides, symptom pages, and wiring diagrams related to P0172.
OEM Manual Evidence
Browse →A L L Diagnostic Trouble Codes ( DTC ) — 2013 GMC Truck Yukon XL Denali AWD V8-6.2L Service Manual | Operation CHARM Operation CHARM : Car...
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Exact Repair Workflows
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Open the exact repair flow most commonly associated with P0172 on this vehicle.
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Exact Vehicle Hubs
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Related Codes
Bank 2 is running rich. If P0172 is also present, look for shared causes like fuel pressure or MAF sensor.
The engine is running lean on bank 1 — too much air or not enough fuel. The ECM has maxed out its fuel trim trying to compensate. Common causes include vacuum leaks and dirty MAF sensors.
Upstream O2 sensor on bank 1 is stuck at high voltage, indicating a rich condition.
Frequently Asked Questions
- Is P0172 dangerous?
- Running rich wastes fuel and can damage the catalytic converter with unburned fuel. Fix within a week.
- Can a dirty air filter cause P0172?
- Yes — a severely clogged air filter restricts airflow, making the mixture rich. Check your air filter first.
Related Repair Guides
If your vehicle has triggered P0172, these DIY repair guides may help: