P0167

P0167 means the bank 2 sensor 3 O2 heater circuit is faulty — the ECM monitors the heater current draw and flags this code when it's outside the expected 0.5-2A operating window (either zero current = open circuit, or excessive current = short circuit). The heater is what brings the sensor element up to its 600F+ light-off temperature in the first 30-60 seconds after cold start so the ECM can enter closed-loop fuel control quickly; without the heater, the sensor takes 5-10 minutes to warm up from exhaust heat alone and the engine runs in open-loop (fixed rich fuel map) the whole time, burning extra fuel and dumping unburned HC into the cat. Cheapest-first ladder: unplug the sensor and ohm the heater pins (typically the two outer pins on a 4-wire sensor) with a DMM — a healthy heater reads 6-15 ohms cold; an open heater reads infinite (OL); a shorted heater reads near 0 ohms. If the heater ohms correctly, the fault is upstream: check the heater B+ feed for 12V with key on (a blown heater fuse takes out multiple sensors at once on most platforms — verify which fuse is shared), and confirm the ECM's heater-driver low-side ground pulses to ground when commanded. A 5-minute heater-element ohm check resolves 70%+ of P0167 calls before any parts get ordered. Expensive-misdiagnosis caveat: corroded connector pins on the heater side increase resistance just enough to push current below the 0.5A threshold without actually breaking the circuit — clean and dielectric-grease the connector before condemning the sensor.

Vehicle-specific patterns: 2004-2010 Ford F-150/Expedition 5.4L 3V throws P0167 from a shared O2 heater fuse blowing when ANY of the four sensors shorts internally — verify which fuse number covers B2S3 before ordering parts. 2007-2014 Toyota Tundra/Sequoia 5.7L 3UR-FE throws P0167 from internal heater element failure around 100-130k miles; the rest of the sensor is fine but the heater opens. 2008-2014 GM Tahoe/Suburban/Yukon 5.3L/6.2L throws P0167 from connector pin-fretting at the rear-bank post-cat sensor where road salt and thermal cycling fatigue the pin contact. 2010-2016 Audi Q7 4.2L V8 / Touareg 4.2L V8 throws P0167 from coolant intrusion via the valley-pan leak onto the post-cat sensor harness — same root cause as the Range Rover 5.0L. Estimated repair: $80 to $450.