OBD-II Code · Sensors
P2273
HO2S Signal Stuck Lean (B2S2)
Downstream O2 sensor on bank 2 stuck reading lean.
Common symptoms
- CEL
Likely causes
- Failed sensor
- Exhaust leak before sensor
- Lean fuel condition
Where to start
- Try the cheapest cause first. Start by checking: failed sensor.
- Cost & scope. $150-$400
- If the code returns after the fix: escalate to a shop or scanner with live-data and freeze-frame. A code that re-sets means the underlying fault is still there.
Read the full diagnostic procedure
P2273 is the Bank 2 downstream O2 stuck-rich fault, mirroring P2271 on the right bank only. Cheapest-first ladder: confirm the issue is bank-specific by overlaying Bank 1 and Bank 2 downstream traces under a 10-second decel fuel cut - both should drop below 0.3 V; if only Bank 2 stays high, the fault is real on that side. Pull Bank 2 long-term fuel trim and injector balance rates. Caveat: a contaminated Bank 2 sensor from oil burn will set P2273 even with perfect fueling - inspect the Bank 2 turbo center section for shaft play and oil weep before condemning the catalyst.
Vehicle-specific patterns
Vehicle-specific patterns: 2011 to 2014 Ford 6.7L Powerstroke set P2273 from Bank 2 injector copper-washer leak overfueling that cylinder; 2007 to 2012 Mercedes Sprinter OM642 set the code from right-bank EGR cooler internal leak; 2011 to 2016 Duramax LML throw P2273 when the Bank 2 downstream sensor is contaminated by DEF over-dosing; 2014 to 2018 Ram EcoDiesel set P2273 from a Bank 2 piston ring failure consuming oil into the exhaust. Estimated repair: $130 to $4,200.
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