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Home / DTC / P0141 — Oxygen sensor(rear) heater

P0141 — Oxygen sensor(rear) heater

Detailed page for trouble code P0141.

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Code

P0141

MITSUBISHI P — Powertrain

Oxygen sensor(rear) heater

Brand: MITSUBISHI
Type: P — Powertrain
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Open or shorted heater element in the rear O2 sensor
  • Broken or corroded wiring or connector to the heater (power or ground)
  • Blown fuse or failed relay supplying the heater circuit
  • Poor ECM/PCM driver or ground connection
  • Aftermarket or failed replacement sensor with incorrect specification
  • Intermittent wiring damage (chafing, rodent) or high resistance connection

Symptoms

  • Malfunction Indicator Lamp (MIL) / Check Engine Light ON
  • Failed emissions test or increased tailpipe emissions
  • Possible rough idle, poor fuel trim adaptions, or reduced fuel economy (if sensor not up to temperature)
  • No obvious engine misfire or roughness if only heater affected (sensor still provides voltage once warm)

What to check

  • Read and record freeze frame and readiness status with scan tool
  • Confirm code is current (not historical) and note any other related codes
  • Visually inspect rear O2 sensor, connector and wiring for damage, corrosion, melted insulation or contamination
  • Check related fuses and relays for the oxygen sensor heater circuit
  • Back-probe connector with key ON to verify heater supply voltage and ground control from ECM
  • Measure heater element resistance at the sensor (engine cold) and compare to specification

Signal parameters

  • Heater resistance (cold): typically ~2–20 ohms (manufacturer spec required)
  • Supply voltage to heater: battery voltage (~11–14 V) when fused power is present
  • ECM driver: switched ground or PWM control — duty varies with temperature and conditions
  • Heater current: can be in the ampere range depending on resistance (I = V/R)
  • Response: heater should draw current when key ON and ECM requests heater operation (scan tool parameter 'Heater ON' or similar)

Diagnostic algorithm

  1. Use a scan tool: read P0141 and any related codes; check freeze frame and live data for rear O2 heater status.
  2. Visually inspect rear O2 sensor and harness for damage, corrosion, or disconnection; repair obvious faults.
  3. With key OFF, disconnect sensor and measure heater resistance across heater pins. Compare to Mitsubishi spec. If open or far out of range, replace sensor.
  4. Check fuse(s) and relay(s) that supply the heater circuit; replace as needed.
  5. With connector connected and key ON (engine OFF), back-probe supply pin to confirm battery voltage is present; then check ECM control/ground pin while commanding heater ON via scan tool. If no supply, trace wiring to fuse/relay; if no control, test ECM ground/driver or wiring to ECM.
  6. Perform continuity and resistance checks on wiring between sensor and fuse/ECM; repair any high resistance or short to ground/power.
  7. If wiring and power are good but heater not driven, test or substitute ECM driver only after confirming harness and supply. Consider module diagnosis at specialist or dealer.
  8. After repairs, clear codes, run self-tests/drive cycle, and verify code does not return and readiness is achieved.

Likely causes

  • Failed rear (downstream) O2 sensor heater
  • Blown heater fuse or faulty relay
  • Damaged or disconnected heater supply/ground wiring or connector corrosion
  • Faulty ECM driver or poor ground at module

Fault status

⚠️ Status
P0141 — Oxygen sensor (rear) heater circuit malfunction. The ECM detected the downstream O2 sensor heater is not functioning within expected parameters and set the code. Inspection of heater circuit, wiring, and sensor required.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours
406

Browse 406 MITSUBISHI manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.

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