P2178 on 2008-2011 Buick Enclave — System Too Rich Off Idle (Bank 1)
1 vehicles · 1 makes
Most Reported On
P2178 is an OBD-II diagnostic trouble code meaning “System Too Rich Off Idle (Bank 1).” The PCM detected that bank 1 is running rich (too much fuel relative to air) during off-idle/cruise conditions, with fuel trims pulling fuel out. A rich condition under load that fuel trim cannot fully correct. This code is most commonly reported on 2008-2011 Buick Enclave.
Common Causes
Diagnostic Tools
To diagnose P2178, 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+).
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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.
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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
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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.
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- Oil reset, EPB, BMS, TPMS, injector coding
- 7-inch touchscreen with Android OS
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FAQ
What does P2178 mean?
P2178 stands for "System Too Rich Off Idle (Bank 1)." The PCM detected that bank 1 is running rich (too much fuel relative to air) during off-idle/cruise conditions, with fuel trims pulling fuel out. A rich condition under load that fuel trim cannot fully correct.
What are the most common causes of P2178?
The most common causes of P2178 are: Leaking/dripping fuel injectors, High fuel pressure / faulty regulator, Dirty/contaminated MAF sensor, Faulty upstream O2 sensor, Restricted air intake. The specific cause varies by vehicle.
How much does it cost to fix P2178?
Repair costs vary widely depending on the root cause and vehicle.
Which vehicles are affected by P2178?
Au7o has documented P2178 across 1 vehicle models from 1 manufacturers: Buick.
Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.