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Home / DTC / P0056 — HO2S Heater Control Circuit Bank 2 Sensor 2

P0056 — HO2S Heater Control Circuit Bank 2 Sensor 2

Detailed page for trouble code P0056.

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P0056

Generic P — Powertrain

HO2S Heater Control Circuit Bank 2 Sensor 2

Brand: Generic
Type: P — Powertrain
Views: UK: 15 EN: 47 RU: 28
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Blown fuse or faulty relay for O2 heater circuit
  • Open or shorted wiring between ECM and sensor heater
  • Corroded, damaged or loose sensor connector
  • Failed oxygen sensor heater element
  • Poor ground or short to battery voltage
  • ECM/PCM output driver failure or internal fault

Symptoms

  • Malfunction Indicator Lamp (MIL) illuminated (check engine light)
  • Failed O2 sensor heater readiness test / emissions readiness incomplete
  • Possible reduced fuel economy or rough running during cold start (sensor slow to heat)
  • Increased exhaust emissions / failed emissions test
  • No obvious drivability symptom in some cases (code may be only indicator)

What to check

  • Read and record freeze frame and pending codes; check for related O2 or exhaust system codes
  • Inspect sensor harness and connector for damage, corrosion, heat damage, or oil/road contamination
  • Check fuse(s) and any relay that supplies O2 heater circuit
  • Backprobe connector with key ON to identify supply voltage and control signal/pinout
  • Measure heater element resistance at the sensor (sensor removed or connector disconnected)
  • Perform voltage drop and continuity tests on both supply and return/ground control circuits

Signal parameters

  • Heater element resistance (typical): approx. 2–20 ohms (varies by sensor). A very high or infinite resistance indicates open heater.
  • Supply voltage at heater fuse/supply: ~11–14 V with ignition ON (engine off) if fused to battery/ignition feed.
  • Control signal from ECM: switched ground or PWM output; measured as duty cycle or switching to complete circuit — may read intermittent voltage when active.
  • Heater current draw when active: commonly 0.3–2 A (varies by sensor) — significantly above or below indicates a problem.
  • No continuity between supply and heater return indicates open circuit; near-short to ground or battery indicates wiring short

Diagnostic algorithm

  1. Retrieve all DTCs and freeze-frame data; note engine temperature at time of code set.
  2. Visually inspect Bank 2 Sensor 2 wiring and connector for damage, corrosion, rodent chew, or heat damage. Repair visible damage before further testing.
  3. Check fuse(s) and any heater relay; replace if blown or suspect. Verify supply at the fuse with ignition ON.
  4. With connector disconnected, measure heater resistance across the sensor heater pins. Compare to expected range; open or very high = bad sensor.
  5. Backprobe harness at the sensor connector with ignition ON (engine off): verify battery/ignition supply on the supply wire and verify PCM control wire behaviour (should switch/ground or show PWM when heater commanded).
  6. If supply is present but heater resistance is open, replace sensor. If supply missing, trace supply back for open/short, check fuse/relay and repair wiring.
  7. If supply present and sensor resistance good but circuit reads short to ground or short to battery, isolate and repair shorted wiring (repair harness, replace connector).
  8. If wiring good but PCM control output shows no switching or abnormal voltages, verify grounds and battery, then consider PCM driver fault — confirm with manufacturer-specific tests before replacing ECM.
  9. Clear codes and perform a test drive/drive cycle to confirm repair and readiness status. Re-scan for reappearance of code.

Likely causes

  • Open heater element inside the Bank 2 Sensor 2 O2 sensor
  • Broken or disconnected harness conductor to sensor heater (pin damage)
  • Water intrusion or corrosion at sensor connector causing high resistance
  • Short to battery or ground in heater supply/return wires
  • Blown/weak fuse or failed heater relay feeding sensor circuit
  • Faulty PCM heater driver (less common)

Fault status

⚠️ Status
Heated oxygen sensor heater control circuit malfunction detected for Bank 2, Sensor 2. ECM has found open, short, or improper control of the heater circuit.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

P0055 P0057 P0036 P0141 P0156
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Code

P0056

HUMMER P — Powertrain

Heated Oxygen Sensor (HO2S) Heater Circuit Bank 2 Sensor 2

Brand: HUMMER
Type: P — Powertrain
Views: UK: 6 EN: 22 RU: 15
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Blown fuse or faulty relay for O2 heater circuit
  • Open or shorted wiring between ECM and sensor heater
  • Corroded, damaged or loose sensor connector
  • Failed oxygen sensor heater element
  • Poor ground or short to battery voltage
  • ECM/PCM output driver failure or internal fault

Symptoms

  • Malfunction Indicator Lamp (MIL) illuminated (check engine light)
  • Failed O2 sensor heater readiness test / emissions readiness incomplete
  • Possible reduced fuel economy or rough running during cold start (sensor slow to heat)
  • Increased exhaust emissions / failed emissions test
  • No obvious drivability symptom in some cases (code may be only indicator)

What to check

  • Read and record freeze frame and pending codes; check for related O2 or exhaust system codes
  • Inspect sensor harness and connector for damage, corrosion, heat damage, or oil/road contamination
  • Check fuse(s) and any relay that supplies O2 heater circuit
  • Backprobe connector with key ON to identify supply voltage and control signal/pinout
  • Measure heater element resistance at the sensor (sensor removed or connector disconnected)
  • Perform voltage drop and continuity tests on both supply and return/ground control circuits

Signal parameters

  • Heater element resistance (typical): approx. 2–20 ohms (varies by sensor). A very high or infinite resistance indicates open heater.
  • Supply voltage at heater fuse/supply: ~11–14 V with ignition ON (engine off) if fused to battery/ignition feed.
  • Control signal from ECM: switched ground or PWM output; measured as duty cycle or switching to complete circuit — may read intermittent voltage when active.
  • Heater current draw when active: commonly 0.3–2 A (varies by sensor) — significantly above or below indicates a problem.
  • No continuity between supply and heater return indicates open circuit; near-short to ground or battery indicates wiring short

Diagnostic algorithm

  1. Retrieve all DTCs and freeze-frame data; note engine temperature at time of code set.
  2. Visually inspect Bank 2 Sensor 2 wiring and connector for damage, corrosion, rodent chew, or heat damage. Repair visible damage before further testing.
  3. Check fuse(s) and any heater relay; replace if blown or suspect. Verify supply at the fuse with ignition ON.
  4. With connector disconnected, measure heater resistance across the sensor heater pins. Compare to expected range; open or very high = bad sensor.
  5. Backprobe harness at the sensor connector with ignition ON (engine off): verify battery/ignition supply on the supply wire and verify PCM control wire behaviour (should switch/ground or show PWM when heater commanded).
  6. If supply is present but heater resistance is open, replace sensor. If supply missing, trace supply back for open/short, check fuse/relay and repair wiring.
  7. If supply present and sensor resistance good but circuit reads short to ground or short to battery, isolate and repair shorted wiring (repair harness, replace connector).
  8. If wiring good but PCM control output shows no switching or abnormal voltages, verify grounds and battery, then consider PCM driver fault — confirm with manufacturer-specific tests before replacing ECM.
  9. Clear codes and perform a test drive/drive cycle to confirm repair and readiness status. Re-scan for reappearance of code.

Likely causes

  • Open heater element inside the Bank 2 Sensor 2 O2 sensor
  • Broken or disconnected harness conductor to sensor heater (pin damage)
  • Water intrusion or corrosion at sensor connector causing high resistance
  • Short to battery or ground in heater supply/return wires
  • Blown/weak fuse or failed heater relay feeding sensor circuit
  • Faulty PCM heater driver (less common)

Fault status

⚠️ Status
Heated oxygen sensor heater control circuit malfunction detected for Bank 2, Sensor 2. ECM has found open, short, or improper control of the heater circuit.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

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Code

P0056

LAND ROVER P — Powertrain

Heated oxygen sensor heater control circuit (bank 2, sensor 2)

Brand: LAND ROVER
Type: P — Powertrain
Views: UK: 4 EN: 20 RU: 12
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Blown fuse or faulty relay for O2 heater circuit
  • Open or shorted wiring between ECM and sensor heater
  • Corroded, damaged or loose sensor connector
  • Failed oxygen sensor heater element
  • Poor ground or short to battery voltage
  • ECM/PCM output driver failure or internal fault

Symptoms

  • Malfunction Indicator Lamp (MIL) illuminated (check engine light)
  • Failed O2 sensor heater readiness test / emissions readiness incomplete
  • Possible reduced fuel economy or rough running during cold start (sensor slow to heat)
  • Increased exhaust emissions / failed emissions test
  • No obvious drivability symptom in some cases (code may be only indicator)

What to check

  • Read and record freeze frame and pending codes; check for related O2 or exhaust system codes
  • Inspect sensor harness and connector for damage, corrosion, heat damage, or oil/road contamination
  • Check fuse(s) and any relay that supplies O2 heater circuit
  • Backprobe connector with key ON to identify supply voltage and control signal/pinout
  • Measure heater element resistance at the sensor (sensor removed or connector disconnected)
  • Perform voltage drop and continuity tests on both supply and return/ground control circuits

Signal parameters

  • Heater element resistance (typical): approx. 2–20 ohms (varies by sensor). A very high or infinite resistance indicates open heater.
  • Supply voltage at heater fuse/supply: ~11–14 V with ignition ON (engine off) if fused to battery/ignition feed.
  • Control signal from ECM: switched ground or PWM output; measured as duty cycle or switching to complete circuit — may read intermittent voltage when active.
  • Heater current draw when active: commonly 0.3–2 A (varies by sensor) — significantly above or below indicates a problem.
  • No continuity between supply and heater return indicates open circuit; near-short to ground or battery indicates wiring short

Diagnostic algorithm

  1. Retrieve all DTCs and freeze-frame data; note engine temperature at time of code set.
  2. Visually inspect Bank 2 Sensor 2 wiring and connector for damage, corrosion, rodent chew, or heat damage. Repair visible damage before further testing.
  3. Check fuse(s) and any heater relay; replace if blown or suspect. Verify supply at the fuse with ignition ON.
  4. With connector disconnected, measure heater resistance across the sensor heater pins. Compare to expected range; open or very high = bad sensor.
  5. Backprobe harness at the sensor connector with ignition ON (engine off): verify battery/ignition supply on the supply wire and verify PCM control wire behaviour (should switch/ground or show PWM when heater commanded).
  6. If supply is present but heater resistance is open, replace sensor. If supply missing, trace supply back for open/short, check fuse/relay and repair wiring.
  7. If supply present and sensor resistance good but circuit reads short to ground or short to battery, isolate and repair shorted wiring (repair harness, replace connector).
  8. If wiring good but PCM control output shows no switching or abnormal voltages, verify grounds and battery, then consider PCM driver fault — confirm with manufacturer-specific tests before replacing ECM.
  9. Clear codes and perform a test drive/drive cycle to confirm repair and readiness status. Re-scan for reappearance of code.

Likely causes

  • Open heater element inside the Bank 2 Sensor 2 O2 sensor
  • Broken or disconnected harness conductor to sensor heater (pin damage)
  • Water intrusion or corrosion at sensor connector causing high resistance
  • Short to battery or ground in heater supply/return wires
  • Blown/weak fuse or failed heater relay feeding sensor circuit
  • Faulty PCM heater driver (less common)

Fault status

⚠️ Status
Heated oxygen sensor heater control circuit malfunction detected for Bank 2, Sensor 2. ECM has found open, short, or improper control of the heater circuit.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

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P0055 P0057 P0036 P0141 P0156
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LAND ROVER 2015 Discovery Sport HSE

HTML Manual
Discovery Sport HSE Years: 2015 Manual in English Sections: 61,541 AI chunks: 61,541
Short description
LAND ROVER · Discovery Sport HSE · 2015
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LAND ROVER 2015 LR4 Base, AWD_result Free Service Manual for the 2015 Land Rover LR4 Base, AW

HTML Manual
LR4 Base, AWD_result Free Service Manual for the 2015 Land Rover LR4 Base, AW Years: 2015 Manual in English Sections: 60,047 AI chunks: 60,047
Short description
LAND ROVER · LR4 Base, AWD_result Free Service Manual for the 2015 Land Rover LR4 Base, AW · 2015
Open manual
Workshop Manuals

Repair manuals for LAND ROVER

3

Land Rover Defender 300Tdi — Workshop Manual (1996 model year)

Workshop Manual
Defender 300Tdi Years: 1996 Manual in English 7.5 MB
Short description

Official workshop manual for the Land Rover Defender 300Tdi (from 1996 model year). Contains specifications, adjustment, fault diagnosis and step-by-step repair and overhaul procedures for engine, transmission, axles, suspension, brakes, electrical and body. Intended for dealer workshops and trained technicians.

199,00 UAH
Contents
Key sections:
  • 01 INTRODUCTION
  • 04 GENERAL SPECIFICATION DATA
  • 05 ENGINE TUNING DATA
  • 07 GENERAL FITTING REMINDERS
  • 09 LUBRICANTS, FLUIDS AND CAPACITIES
  • 10 MAINTENANCE
  • 12 ENGINE Tdi
  • - Description and operation
  • - Fault diagnosis
  • - Adjustment
  • - Repair and overhaul procedures
  • 19 FUEL SYSTEM Tdi
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Land Rover Defender Workshop Manual Supplement & Body Repair Manual (1999 & 2002 MY)

Workshop Manual
Defender Years: 1999–2002 Manual in English 7.6 MB
Short description

Workshop Manual Supplement and Body Repair Manual for the Land Rover Defender. Includes general specifications, maintenance schedules, tuning data and step‑by‑step repair procedures for engine, transmission, suspension, brakes, electrical and body repairs. Covers Defender models from 1999 and 2002 model years.

199,00 UAH
Contents
Key sections:
  • 01 - INTRODUCTION
  • - Introduction
  • - Dimensions
  • - References
  • - Repairs and replacements
  • - Poisonous substances
  • - Fuel handling precautions
  • - Synthetic rubber
  • - Recommended sealants
  • - Used engine oil precautions
  • - Accessories and conversions
  • - Wheels and tyres
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Land Rover Range Rover — Electrical Library (LRL 0453ENG, 2002)

Workshop Manual
Manual in English Pages: 494 7.1 MB
Short description

Land Rover Range Rover Electrical Library (LRL 0453ENG). Comprehensive manual covering fuse details, earth points, system descriptions, diagnostics and connector pin-outs for electrical troubleshooting and repair. Intended for technicians and service workshops.

199,00 UAH
Contents
Key sections:
  • 1 INTRODUCTION
  • 1.1 About this document
  • 1.2 Battery voltage
  • 1.3 Electrical precautions
  • 1.4 Battery disconnecting / charging
  • 1.5 Disciplines / greases
  • 1.6 Abbreviations
  • 1.7 HeVAC, sensors abbreviations
  • 1.8 How to use this document
  • 1.9 Connector detail format
  • 1.10 Fault diagnosis
  • 1.11 Wire colour codes
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