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Home / DTC / P0037 — HO2S Heater Control Circuit Low Bank 1 Sensor 2

P0037 — HO2S Heater Control Circuit Low Bank 1 Sensor 2

Detailed page for trouble code P0037.

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Code

P0037

Generic P — Powertrain

HO2S Heater Control Circuit Low Bank 1 Sensor 2

Brand: Generic
Type: P — Powertrain
Views: UK: 26 EN: 54 RU: 40
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Open or high-resistance heater element in the Bank 1 Sensor 2 O2 sensor
  • Broken, corroded or disconnected heater wiring or connector
  • Short to ground in heater supply or control circuit
  • Blown fuse or faulty relay supplying the heater circuit
  • Faulty PCM/ECM heater driver
  • Incorrect or non‑OEM replacement sensor (wrong heater resistance/spec)

Symptoms

  • Malfunction Indicator Lamp (MIL) illuminated
  • Possible increased fuel consumption and richer/leaner running
  • Failed emissions/evap readiness or oxygen sensor heater monitors not ready
  • Poor catalytic converter efficiency over time
  • No immediate drivability issue in many cases (downstream sensor primarily affects emissions)

What to check

  • Read and record freeze frame and related codes; clear codes and re-check
  • Visual inspection of sensor connector and wiring for damage, corrosion or disconnection
  • Verify relevant fuse(s) and relay(s) for the heater circuit
  • Measure heater element resistance at the sensor (with connector disconnected)
  • Back-probe heater supply and ground with key ON to verify voltage and PCM control signal

Signal parameters

  • Heater supply voltage (key ON, engine OFF): ~12 V (or battery voltage) present at supply circuit
  • Heater element resistance (typical): commonly 2–20 ohms depending on sensor — consult vehicle spec
  • PCM driver output: switched ground or PWM driver — should show switching when heater commanded
  • Downstream O2 sensor signal (separate): ~0–1 V but heater fault concerns heater circuit only
  • Current draw when heater active: often 0.5–2 A depending on sensor (use clamp meter if available)

Diagnostic algorithm

  1. Retrieve codes and freeze frame; note related heater or oxygen sensor codes (e.g., P0036, P0141).
  2. Perform visual inspection: check Bank 1 Sensor 2 connector, wiring harness, and underbody for damage, corrosion, or rodent chew.
  3. Locate and check fuse(s)/relay(s) for the O2 heater circuit; replace if blown and retest—if fuse blows again, suspect short.
  4. With ignition OFF, disconnect sensor connector and measure heater element resistance between heater pins. Compare to vehicle spec. Infinite/very high = open element; very low/near 0 = short.
  5. With key ON (engine OFF), back-probe the connector: verify battery voltage on the heater supply lead and verify PCM control on the other lead (ground switching or PWM).
  6. If supply voltage is missing, trace wiring back to fuse/relay/ECU to find open. If supply present but PCM control absent or stuck, test PCM ground/driver circuits and wiring for short to ground.
  7. If wiring and power are good but heater resistance is out of spec, replace the downstream O2 sensor with OEM or equivalent and clear codes.
  8. If suspicion remains on PCM heater driver, compare signals to known-good CPU output or perform wiggle/continuity tests. Replace PCM only after eliminating wiring and sensor faults.
  9. After repair, clear codes, confirm the heater command and operation, then perform a driving cycle/emissions readiness check to verify the code does not return.

Likely causes

  • Damaged connector at downstream O2 sensor (water/corrosion)
  • Heater element failed (open circuit) inside sensor
  • Pinched or chafed wiring to sensor causing short to ground
  • Blown 10A/20A fuse for O2 heater circuit
  • PCM driver fault (less common)

Fault status

⚠️ Status
HO2S Heater Control Circuit Low — Bank 1 Sensor 2 (heater circuit low/open/short)
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours
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Code

P0037

HUMMER P — Powertrain

Heated Oxygen Sensor (HO2S) Heater Circuit Low Voltage Bank 1 Sensor 2

Brand: HUMMER
Type: P — Powertrain
Views: UK: 10 EN: 28 RU: 18
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Open or high-resistance heater element in the Bank 1 Sensor 2 O2 sensor
  • Broken, corroded or disconnected heater wiring or connector
  • Short to ground in heater supply or control circuit
  • Blown fuse or faulty relay supplying the heater circuit
  • Faulty PCM/ECM heater driver
  • Incorrect or non‑OEM replacement sensor (wrong heater resistance/spec)

Symptoms

  • Malfunction Indicator Lamp (MIL) illuminated
  • Possible increased fuel consumption and richer/leaner running
  • Failed emissions/evap readiness or oxygen sensor heater monitors not ready
  • Poor catalytic converter efficiency over time
  • No immediate drivability issue in many cases (downstream sensor primarily affects emissions)

What to check

  • Read and record freeze frame and related codes; clear codes and re-check
  • Visual inspection of sensor connector and wiring for damage, corrosion or disconnection
  • Verify relevant fuse(s) and relay(s) for the heater circuit
  • Measure heater element resistance at the sensor (with connector disconnected)
  • Back-probe heater supply and ground with key ON to verify voltage and PCM control signal

Signal parameters

  • Heater supply voltage (key ON, engine OFF): ~12 V (or battery voltage) present at supply circuit
  • Heater element resistance (typical): commonly 2–20 ohms depending on sensor — consult vehicle spec
  • PCM driver output: switched ground or PWM driver — should show switching when heater commanded
  • Downstream O2 sensor signal (separate): ~0–1 V but heater fault concerns heater circuit only
  • Current draw when heater active: often 0.5–2 A depending on sensor (use clamp meter if available)

Diagnostic algorithm

  1. Retrieve codes and freeze frame; note related heater or oxygen sensor codes (e.g., P0036, P0141).
  2. Perform visual inspection: check Bank 1 Sensor 2 connector, wiring harness, and underbody for damage, corrosion, or rodent chew.
  3. Locate and check fuse(s)/relay(s) for the O2 heater circuit; replace if blown and retest—if fuse blows again, suspect short.
  4. With ignition OFF, disconnect sensor connector and measure heater element resistance between heater pins. Compare to vehicle spec. Infinite/very high = open element; very low/near 0 = short.
  5. With key ON (engine OFF), back-probe the connector: verify battery voltage on the heater supply lead and verify PCM control on the other lead (ground switching or PWM).
  6. If supply voltage is missing, trace wiring back to fuse/relay/ECU to find open. If supply present but PCM control absent or stuck, test PCM ground/driver circuits and wiring for short to ground.
  7. If wiring and power are good but heater resistance is out of spec, replace the downstream O2 sensor with OEM or equivalent and clear codes.
  8. If suspicion remains on PCM heater driver, compare signals to known-good CPU output or perform wiggle/continuity tests. Replace PCM only after eliminating wiring and sensor faults.
  9. After repair, clear codes, confirm the heater command and operation, then perform a driving cycle/emissions readiness check to verify the code does not return.

Likely causes

  • Damaged connector at downstream O2 sensor (water/corrosion)
  • Heater element failed (open circuit) inside sensor
  • Pinched or chafed wiring to sensor causing short to ground
  • Blown 10A/20A fuse for O2 heater circuit
  • PCM driver fault (less common)

Fault status

⚠️ Status
HO2S Heater Control Circuit Low — Bank 1 Sensor 2 (heater circuit low/open/short)
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours
Your experience will help others
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Keep it short and practical. Up to 500 characters.
Send to email
Code

P0037

LAND ROVER P — Powertrain

Circuit of the heated oxygen sensor heater control low (bank 1 sensor 2)

Brand: LAND ROVER
Type: P — Powertrain
Views: UK: 6 EN: 20 RU: 12
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Open or high-resistance heater element in the Bank 1 Sensor 2 O2 sensor
  • Broken, corroded or disconnected heater wiring or connector
  • Short to ground in heater supply or control circuit
  • Blown fuse or faulty relay supplying the heater circuit
  • Faulty PCM/ECM heater driver
  • Incorrect or non‑OEM replacement sensor (wrong heater resistance/spec)

Symptoms

  • Malfunction Indicator Lamp (MIL) illuminated
  • Possible increased fuel consumption and richer/leaner running
  • Failed emissions/evap readiness or oxygen sensor heater monitors not ready
  • Poor catalytic converter efficiency over time
  • No immediate drivability issue in many cases (downstream sensor primarily affects emissions)

What to check

  • Read and record freeze frame and related codes; clear codes and re-check
  • Visual inspection of sensor connector and wiring for damage, corrosion or disconnection
  • Verify relevant fuse(s) and relay(s) for the heater circuit
  • Measure heater element resistance at the sensor (with connector disconnected)
  • Back-probe heater supply and ground with key ON to verify voltage and PCM control signal

Signal parameters

  • Heater supply voltage (key ON, engine OFF): ~12 V (or battery voltage) present at supply circuit
  • Heater element resistance (typical): commonly 2–20 ohms depending on sensor — consult vehicle spec
  • PCM driver output: switched ground or PWM driver — should show switching when heater commanded
  • Downstream O2 sensor signal (separate): ~0–1 V but heater fault concerns heater circuit only
  • Current draw when heater active: often 0.5–2 A depending on sensor (use clamp meter if available)

Diagnostic algorithm

  1. Retrieve codes and freeze frame; note related heater or oxygen sensor codes (e.g., P0036, P0141).
  2. Perform visual inspection: check Bank 1 Sensor 2 connector, wiring harness, and underbody for damage, corrosion, or rodent chew.
  3. Locate and check fuse(s)/relay(s) for the O2 heater circuit; replace if blown and retest—if fuse blows again, suspect short.
  4. With ignition OFF, disconnect sensor connector and measure heater element resistance between heater pins. Compare to vehicle spec. Infinite/very high = open element; very low/near 0 = short.
  5. With key ON (engine OFF), back-probe the connector: verify battery voltage on the heater supply lead and verify PCM control on the other lead (ground switching or PWM).
  6. If supply voltage is missing, trace wiring back to fuse/relay/ECU to find open. If supply present but PCM control absent or stuck, test PCM ground/driver circuits and wiring for short to ground.
  7. If wiring and power are good but heater resistance is out of spec, replace the downstream O2 sensor with OEM or equivalent and clear codes.
  8. If suspicion remains on PCM heater driver, compare signals to known-good CPU output or perform wiggle/continuity tests. Replace PCM only after eliminating wiring and sensor faults.
  9. After repair, clear codes, confirm the heater command and operation, then perform a driving cycle/emissions readiness check to verify the code does not return.

Likely causes

  • Damaged connector at downstream O2 sensor (water/corrosion)
  • Heater element failed (open circuit) inside sensor
  • Pinched or chafed wiring to sensor causing short to ground
  • Blown 10A/20A fuse for O2 heater circuit
  • PCM driver fault (less common)

Fault status

⚠️ Status
HO2S Heater Control Circuit Low — Bank 1 Sensor 2 (heater circuit low/open/short)
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours
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
Buy

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
Buy

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
Buy
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Code

P0037

MITSUBISHI P — Powertrain

Oxygen sensor heater(rear) low

Brand: MITSUBISHI
Type: P — Powertrain
Views: UK: 10 EN: 25 RU: 18
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Page language: EN

Causes

  • Open or high-resistance heater element in the Bank 1 Sensor 2 O2 sensor
  • Broken, corroded or disconnected heater wiring or connector
  • Short to ground in heater supply or control circuit
  • Blown fuse or faulty relay supplying the heater circuit
  • Faulty PCM/ECM heater driver
  • Incorrect or non‑OEM replacement sensor (wrong heater resistance/spec)

Symptoms

  • Malfunction Indicator Lamp (MIL) illuminated
  • Possible increased fuel consumption and richer/leaner running
  • Failed emissions/evap readiness or oxygen sensor heater monitors not ready
  • Poor catalytic converter efficiency over time
  • No immediate drivability issue in many cases (downstream sensor primarily affects emissions)

What to check

  • Read and record freeze frame and related codes; clear codes and re-check
  • Visual inspection of sensor connector and wiring for damage, corrosion or disconnection
  • Verify relevant fuse(s) and relay(s) for the heater circuit
  • Measure heater element resistance at the sensor (with connector disconnected)
  • Back-probe heater supply and ground with key ON to verify voltage and PCM control signal

Signal parameters

  • Heater supply voltage (key ON, engine OFF): ~12 V (or battery voltage) present at supply circuit
  • Heater element resistance (typical): commonly 2–20 ohms depending on sensor — consult vehicle spec
  • PCM driver output: switched ground or PWM driver — should show switching when heater commanded
  • Downstream O2 sensor signal (separate): ~0–1 V but heater fault concerns heater circuit only
  • Current draw when heater active: often 0.5–2 A depending on sensor (use clamp meter if available)

Diagnostic algorithm

  1. Retrieve codes and freeze frame; note related heater or oxygen sensor codes (e.g., P0036, P0141).
  2. Perform visual inspection: check Bank 1 Sensor 2 connector, wiring harness, and underbody for damage, corrosion, or rodent chew.
  3. Locate and check fuse(s)/relay(s) for the O2 heater circuit; replace if blown and retest—if fuse blows again, suspect short.
  4. With ignition OFF, disconnect sensor connector and measure heater element resistance between heater pins. Compare to vehicle spec. Infinite/very high = open element; very low/near 0 = short.
  5. With key ON (engine OFF), back-probe the connector: verify battery voltage on the heater supply lead and verify PCM control on the other lead (ground switching or PWM).
  6. If supply voltage is missing, trace wiring back to fuse/relay/ECU to find open. If supply present but PCM control absent or stuck, test PCM ground/driver circuits and wiring for short to ground.
  7. If wiring and power are good but heater resistance is out of spec, replace the downstream O2 sensor with OEM or equivalent and clear codes.
  8. If suspicion remains on PCM heater driver, compare signals to known-good CPU output or perform wiggle/continuity tests. Replace PCM only after eliminating wiring and sensor faults.
  9. After repair, clear codes, confirm the heater command and operation, then perform a driving cycle/emissions readiness check to verify the code does not return.

Likely causes

  • Damaged connector at downstream O2 sensor (water/corrosion)
  • Heater element failed (open circuit) inside sensor
  • Pinched or chafed wiring to sensor causing short to ground
  • Blown 10A/20A fuse for O2 heater circuit
  • PCM driver fault (less common)

Fault status

⚠️ Status
HO2S Heater Control Circuit Low — Bank 1 Sensor 2 (heater circuit low/open/short)
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours
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