P0172: System Too Rich (Bank 1)
9 vehicles · 8 makes
P0172 is an OBD-II diagnostic trouble code meaning “System Too Rich (Bank 1).” The engine is running rich on Bank 1 — too much fuel or not enough air. Opposite of P0171 lean condition. This code appears across 9 vehicle models from 8 manufacturers.
Common Causes
Diagnostic Tools
To diagnose P0172, you'll need an OBD-II scanner. Here are our recommendations at every price point.
ANCEL AD310 Classic OBD-II Scanner
by ANCEL
A simple, affordable code reader that reads and clears check engine codes. Great for quick diagnostics on any OBD-II vehicle (1996+).
- Read & clear engine codes
- View freeze frame data
- I/M readiness status
- No batteries or app needed
BlueDriver Pro Bluetooth Scanner
by BlueDriver
Bluetooth OBD-II scanner with a free companion app. Provides enhanced diagnostics, smog readiness, and repair reports sourced from a database of verified fixes.
- Enhanced diagnostics (ABS, SRS, transmission)
- Repair Reports with verified fixes
- Smog check readiness
- Free app (iOS & Android)
LAUNCH CRP123X OBD-II Scanner
by LAUNCH
A professional-grade handheld scanner that reads all four major systems (engine, transmission, ABS, SRS) with live data streaming and graphing.
- Engine, transmission, ABS, SRS diagnostics
- Live data stream & graphing
- AutoVIN for vehicle identification
- Free lifetime updates via Wi-Fi
Autel MaxiCOM MK808S Diagnostic Tool
by Autel
Shop-level diagnostic tablet with bi-directional control, active tests, and full system coverage. Ideal for serious DIYers and small shops.
- All-system diagnostics (25+ modules)
- Bi-directional control & active tests
- Oil reset, EPB, BMS, TPMS, injector coding
- 7-inch touchscreen with Android OS
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Vehicles Affected (9)
FAQ
What does P0172 mean?
P0172 stands for "System Too Rich (Bank 1)." The engine is running rich on Bank 1 — too much fuel or not enough air. Opposite of P0171 lean condition.
What are the most common causes of P0172?
The most common causes of P0172 are: Leaking fuel injector, Faulty fuel pressure regulator, Dirty MAF sensor reading low, Stuck closed EVAP purge valve, Faulty O2 sensor. The specific cause varies by vehicle.
How much does it cost to fix P0172?
Repair costs vary widely depending on the root cause and vehicle.
Which vehicles are affected by P0172?
Au7o has documented P0172 across 9 vehicle models from 8 manufacturers: BMW, Ford, GMC, Kia, Mercedes-Benz, Nissan, Subaru, Volvo.
Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.