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P0160 Generic (SAE)

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

Updated 2026-10-02 · Fuel & air metering

Severity
Low
Typical repair cost
30 – 280 EUR
System
Powertrain

What it means

The bank 2 downstream oxygen sensor has produced no voltage change at all over the monitoring period – the signal sits at the ECU bias (about 0.45 V) or at 0 V even when the ECU forces the mixture rich and lean. Bank 2 is the bank without cylinder 1. A rear sensor is expected to move slowly, so the ECU only sets P0160 after a long observation window; the usual causes are an open signal circuit, a dead element, or a cold sensor due to a failed heater (P0161).

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Symptoms

  • Check engine light after an extended drive
  • Catalyst and O2 sensor readiness monitors for bank 2 never set
  • Often paired with P0161 (heater) when the sensor is cold
  • No driveability complaint in nearly all cases
  • Possible slight increase in consumption on vehicles using rear-sensor trim

Common causes

  1. Broken signal wire or disconnected plug under the car (frequent after clutch, gearbox or exhaust work)
  2. Dead sensor element with an internal open circuit
  3. Heater failure leaving the sensor too cold – the rear sensor sees cooler gas and depends more on its heater
  4. Connector flooded with water or packed with road salt corrosion
  5. Harness chafed through on a heat shield or driveshaft
  6. Blown shared heater fuse or relay

How to diagnose

  1. Check for P0161 alongside: if the heater code is present, a cold sensor explains the missing signal, and heater resistance (2-15 ohm expected, infinite when open) tells you whether the sensor itself failed
  2. Look at the plug and pigtail under the car first – this sensor sits in the most exposed location of all four and unplugged or broken wiring accounts for a large share of P0160 cases
  3. Key on, engine off: B2S2 should show the ECU bias of about 0.45 V on the scan tool; 0 V indicates a short to ground, 5 V a short to reference, and both rule out the sensor as the sole cause
  4. Fully warm the engine, hold 2500 rpm, then introduce propane briefly: a working rear sensor must climb above 0.7 V within a few seconds and fall below 0.3 V after a snap throttle
  5. If the multimeter at the sensor connector shows the sensor moving between 0.1 and 0.9 V but the scan tool stays flat, repair the open signal wire to the ECU (continuity under 1 ohm)
  6. Swap bank 1 and bank 2 rear sensors if the connectors match: a code that migrates to bank 1 confirms a dead sensor

Frequently asked questions

Why did this appear right after a gearbox job?

The bank 2 rear sensor plug is often unclipped or its wiring pulled during transmission or exhaust removal. Check the connector before anything else.

Is it safe to keep driving?

Yes. Sensor 2 does not control fuelling, so the engine runs normally. The only consequence is a failed OBD inspection until it is fixed.

How long does the ECU take to set P0160 after a repair is done wrong?

Usually one or two complete drive cycles with 10-15 minutes of warm running each, since the catalyst monitor has strict enable conditions.

Related codes

P0156P0159P0161P0154P0140

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