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Home / DTC / P0165 — Oxygen sensor - slow response circuit. Bank 2 - sensor 3

P0165 — Oxygen sensor - slow response circuit. Bank 2 - sensor 3

Detailed page for trouble code P0165.

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P0165

LAND ROVER P — Powertrain

Oxygen sensor - slow response circuit. Bank 2 - sensor 3

Brand: LAND ROVER
Type: P — Powertrain
AI status
Completed
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Completed 100%
Page language: EN

Causes

  • Aging or failed oxygen sensor (contaminated or worn)
  • Open, shorted, or corroded wiring or connector to the sensor
  • Heater circuit failure or intermittent heater power/ground
  • Exhaust leak near the sensor or manifold causing false readings
  • Contamination from oil, coolant, silicone, or fuel additives
  • Catalytic converter degradation affecting downstream signal

Symptoms

  • Malfunction Indicator Lamp (MIL) illuminated (check engine light)
  • Possible failed emissions test
  • Reduced ability to monitor catalyst efficiency (may not directly affect drivability)
  • Occasional rough idle or hesitation if related to other fuel trim issues

What to check

  • Read freeze frame and all stored/related codes with a good scan tool
  • Visual inspection of sensor, connector and wiring for damage, corrosion, or heat damage
  • Inspect exhaust for leaks around banks and sensor location
  • Compare live data of upstream (bank 2 sensor 1) and downstream (bank 2 sensor 3) O2 signals while engine is at operating temperature
  • Backprobe sensor connector to verify 12V power and ground for heater circuit (with key on/engine off and during run)
  • Measure heater resistance at the sensor and compare to manufacturer spec

Signal parameters

  • Typical narrowband sensor signal: ~0.1–0.9 V (manufacturer dependent)
  • Downstream (post-catalyst) sensors usually show smaller, slower fluctuations and often ~0.4–0.6 V steady at idle — slow or no switching indicates a problem
  • Upstream sensor switching frequency typically ~1–3 Hz when healthy; downstream should be more stable
  • Heater circuit resistance: typically low (single to low tens of ohms) — compare to vehicle specification
  • Heater supply: 12 V switched feed and a good ground (measure for presence/continuity)
  • Response time: switching lag significantly greater than the upstream sensor under the same conditions indicates a slow-response fault

Diagnostic algorithm

  1. Retrieve freeze-frame data and note engine conditions when the code set (temperature, load, fuel trims).
  2. Perform a full scan for related codes (heater, upstream sensors, fuel trim, catalyst codes) and address any clearly related faults first.
  3. Visually inspect Bank 2 Sensor 3 wiring, connector, and sensor for contamination, damage, heat chafing, or corrosion. Repair or replace damaged wiring/connectors.
  4. Inspect the exhaust near the sensor for leaks or damage; repair any leaks and retest.
  5. With engine at normal operating temperature, monitor live data: compare bank 2 upstream and bank 2 sensor 3 voltages while inducing a rich/lean change (snap throttle or introduce small propane/vacuum change) to observe sensor response speed.
  6. Backprobe and verify heater circuit: check for battery voltage feed with key on and continuity to ground when commanded; measure heater resistance at the sensor and compare to spec.
  7. If wiring, power, and ground are good but signal still slow, swap or substitute a known-good sensor (or bench-test) and re-evaluate. Replace sensor if confirmed faulty.
  8. If new sensor behaves similarly, investigate catalytic converter function and exhaust restrictions, and verify ECU operation/software updates.
  9. Clear codes and perform a road/drive-cycle test to confirm the repair and ensure the code does not return.

Likely causes

  • Failed downstream oxygen sensor (Bank 2 Sensor 3)
  • Heater circuit not reaching operating temperature (open/short or no power/ground)
  • Damaged wiring harness or poor connector contact
  • Exhaust leak or downstream catalytic converter problem causing abnormally slow or damped signal

Fault status

⚠️ Status
MIL on — Oxygen sensor slow response circuit detected (Bank 2 Sensor 3). Possible faulty sensor, heater, wiring, or exhaust/catalyst issue.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1.0 - 2.5 hours
320

Browse 320 LAND ROVER manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.

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