P0167

O2 Sensor Heater Circuit Malfunction (Bank 2 Sensor 3)

P0167 is a generic OBD-II powertrain diagnostic trouble code: O2 Sensor Heater Circuit Malfunction (Bank 2 Sensor 3). It is logged by the engine control unit when the o2/lambda monitor detects that a specific fault threshold has been exceeded — typically resulting in the malfunction-indicator lamp (MIL / check-engine light) being illuminated.

Code
P0167
Group
Powertrain
System
O2/Lambda
Severity
Warning (MIL on)
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What P0167 means

P0167 is set when the PCM detects a malfunction in the heater circuit of the Bank 2 Sensor 3 oxygen sensor. Modern heated exhaust gas oxygen (HEGO) sensors include an internal resistance heater element that brings the zirconia or titania sensing cell to its operating temperature range of approximately 315–650 °C within 30–60 seconds of cold-engine start. The PCM monitors heater circuit current draw or switching duty cycle; if the measured parameter falls outside calibrated limits — indicating an open, short, or excessively high-resistance circuit — P0167 is stored.

The fault can originate at three locations: the heater element inside the sensor itself (internal open coil or short to ground), the wiring harness between the sensor and the PCM (broken strand, corroded connector, or chafed insulation), or the heater circuit fuse/relay in the PDC. A heater that draws too much current (internal short) will typically blow the fuse; a heater that draws too little (open coil or broken wire) will set P0167 without a blown fuse. The PCM may also detect the fault if PCM-side driver circuitry that controls heater pulse-width modulation is degraded.

P0167 on its own does not prevent the engine from starting or running, but a cold sensor will respond slowly or not at all, which can trigger secondary codes such as P0165 or P0166 and impair catalyst efficiency monitoring. Fuel economy may suffer slightly during extended cold-start periods when the PCM runs in open-loop enrichment longer than normal. Diagnosis is straightforward and sensor replacement resolves the majority of cases.

Common causes

Most-frequently reported root causes when P0167 is logged.

  • 1
    Failed internal heater coil within the B2S3 sensor (open circuit — most common cause).
  • 2
    Internal heater-to-ground short within the sensor, causing excessive current draw and a blown heater fuse.
  • 3
    Blown heater circuit fuse in the fuse/power distribution box cutting supply voltage to the sensor.
  • 4
    Open circuit or broken strand in the heater supply or ground wire between the PDC and sensor connector.
  • 5
    Corroded, spread, or fully separated connector pins at the sensor harness plug causing high-resistance or no connection.
  • 6
    Chafed heater wire contacting an exhaust component and shorting to ground.
  • 7
    PCM heater driver circuit fault causing incorrect pulse-width output to the heater element.

Symptoms drivers notice

Check Engine Light (MIL) illuminates with P0167 stored.
Extended cold-start open-loop fuelling period — engine may run slightly rich until the sensor warms passively from exhaust heat alone.
Secondary codes P0165 (slow response) or P0166 (no activity) may be present if the unheated sensor fails to activate.
Marginal reduction in fuel economy, especially on short cold-start trips where the sensor never self-heats sufficiently.
Catalyst efficiency monitor for Bank 2 may not complete due to the sensor's delayed or absent signal.

How to diagnose P0167

A typical diagnostic flow when this code is present.

  1. 1
    Retrieve all stored codes; note whether P0165 or P0166 is also present, as this indicates the heater failure is severe enough to prevent sensor activation.
  2. 2
    Locate and inspect the heater circuit fuse for the B2S3 sensor (refer to vehicle fuse diagram); replace a blown fuse and retest — if it blows again, suspect an internal heater short in the sensor.
  3. 3
    Visually inspect the sensor harness from the bung connector along the exhaust tunnel routing for chafing, heat damage, or corrosion at connectors.
  4. 4
    With the ignition off and sensor disconnected, measure heater element resistance across the two heater pins (consult the vehicle wiring diagram for pin identification); the normal range is typically 2–10 Ω — an open reading (OL) confirms a failed heater coil.
  5. 5
    With the ignition on and sensor disconnected, measure battery voltage at the heater supply pin of the harness connector; no voltage indicates an open supply wire or blown fuse upstream.
  6. 6
    If heater resistance and supply voltage are correct, back-probe the PCM-side heater control wire with a scan tool or oscilloscope to verify the PCM is generating a PWM heater-control signal.
  7. 7
    Replace the sensor if the heater coil is open or out of range; clear codes and perform a cold-start drive cycle to confirm P0167 does not return.

Related powertrain codes

Frequently asked questions

Why does an O2 sensor need a heater?

Zirconia oxygen sensors only produce accurate voltage signals above approximately 315 °C. At cold start, exhaust gas temperature is too low to heat the sensor quickly enough for closed-loop operation. The integrated heater brings the sensor to operating temperature within 30–60 seconds, allowing the PCM to enter closed-loop fuelling much sooner and reducing cold-start emissions and fuel consumption.

What resistance should the heater element read?

Most OEM sensors specify 2–10 Ω across the heater pins, measured with the ignition off and the sensor disconnected. Readings outside this range — particularly an open circuit (OL) — indicate a failed heater and the sensor should be replaced. Always cross-reference with the manufacturer's service data for the specific application.

If I replace the fuse and it blows again, what should I check?

A repeatedly blown heater fuse almost always indicates an internal short in the sensor's heater element. Replace the B2S3 sensor first. If the fuse blows again after sensor replacement, inspect the harness for a short to ground caused by chafed insulation contacting the exhaust pipe or body, then test the PCM heater driver circuit.

Can P0167 cause a failed emissions test?

Yes, in two ways. First, if the sensor never activates due to heater failure, the catalyst efficiency monitor cannot run, leaving the OBD readiness monitor in a 'not ready' state — most jurisdictions fail a vehicle with incomplete readiness monitors. Second, prolonged open-loop fuelling from a cold sensor can increase tailpipe emissions during the test.

Disabling P0167 in software

RaceTune can permanently disable P0167 — and any other OBD-II diagnostic trouble code — on every ECU family we support. The monitor is disabled inside the ECU itself, so the fault stops being logged: the warning light stays off and the engine never enters limp mode for this code. The change is tied to your exact software version.

Permanent
The monitor is disabled in the ECU itself — not just cleared. It cannot return.
Tailored to your file
Each patch is matched to your specific software version — never a one-size-fits-all file.
Reversible
The original file is always preserved. Reflash the stock to return the ECU to factory state.

Software modifications affect emissions compliance and are not road-legal in many jurisdictions. RaceTune service files are intended for motorsport, off-road, and export use.

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