P0167

O2 Sensor Circuit No Activity Detected (Bank 2 Sensor 3)

Powertrain Emission Controls O2 Sensor Circuit 🟡 Moderate — Fix within a week ⚠️ Drive with Care
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What This Actually Means

In plain language — no jargon

Your engine's oxygen sensor on Bank 2, Sensor 3 isn't sending any signal to the computer—it's like a silent smoke detector that should be alerting but isn't making a peep. The ECU expects to hear electrical activity from this sensor, but it's detecting nothing.

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Symptoms You May Notice

3 known symptoms for this code
Check Engine Light illuminated
Possible rough idle or reduced fuel economy
May have no noticeable drivability issues initially
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How Your ECU Detects This

Technical sensor logic and voltage thresholds

The ECU monitors the O2 sensor's voltage signal over time, expecting oscillations between 0.1V and 0.9V as the engine cycles rich and lean. Bank 2 Sensor 3 is the downstream catalyst monitor sensor. When the ECU detects zero voltage activity or a flat-line signal for a set duration, it triggers this fault.

Voltage & Parameter Thresholds

ParameterNormal RangeFault Condition
Sensor voltage oscillation 0.1V–0.9V with frequent transitions No signal activity or constant voltage <0.1 seconds
Response time <100ms voltage change No response detected over monitoring period
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Diagnostic & DIY Fix Guide

Check these in order — from cheapest to most complex
1
Oxygen sensor connector
Inspect and reseat the O2 sensor connector; corrosion or loose pins often cause no-signal faults.
2
Oxygen sensor wiring harness
Check for damaged, corroded, or disconnected wires between the sensor and ECU; repair or replace as needed.
3
Oxygen sensor (Bank 2, Sensor 3)
Replace the sensor if wiring and connectors are good; failed internal heater or sensing element is common.
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When to See a Professional Mechanic

Not all fault codes are safe to DIY

Code P0167 is a moderate fault. You can generally drive to a workshop, but avoid long trips or high-load driving (motorway, uphill towing) until it is diagnosed. If the code keeps returning after clearing, or if you notice the symptoms listed above worsening, do not delay professional diagnosis. Many moderate codes have multiple possible root causes — a mechanic with live OBD data can identify the exact fault more efficiently than part-by-part trial and error.

Safety note: OBD-II codes identify the system or circuit where a fault was detected — they do not always identify the exact failed component. A professional mechanic using live sensor data will diagnose the root cause more accurately than replacing parts based on the code alone.
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How to Clear Code P0167

What happens after you fix the fault

Once the fault is repaired, P0167 can be cleared using any OBD-II scanner. Connect the scanner, navigate to "Clear Codes" or "Erase DTCs," and confirm. The check engine light turns off immediately.

The code will return if the root cause was not actually fixed. The ECM re-detects the fault within 1–3 drive cycles and sets the code again.

✅ Safe to Clear When
  • Fault has been diagnosed and repaired
  • You want to confirm the repair worked
  • Code appeared after a sensor was cleaned
⚠️ Do Not Clear When
  • Preparing for an emissions/PUC test
  • Root cause is still undiagnosed
  • Check engine light is flashing
Emissions test note: Clearing codes resets OBD readiness monitors. Most vehicles need 50–100 km of mixed driving before monitors complete. Do not clear codes immediately before an emissions or PUC inspection.