Code
P0142
Generic
P — Powertrain
O2 Sensor Circuit Bank 1 Sensor 3
Views:
UK: 11
EN: 25
RU: 18
AI status
Completed
Completed
100%
Causes
- Faulty O2 sensor (Bank 1 Sensor 3)
- Open, shorted or corroded sensor wiring or connector
- Poor ground or reference voltage to the sensor or heater circuit
- Exhaust leak upstream of the sensor
- Contaminated sensor (oil, coolant, silicone, leaded fuel)
- Failed PCM/ECM or internal driver fault
Symptoms
- Check Engine Light (MIL) on
- Failed emissions/inspection test
- Little or no noticeable drivability change in many vehicles
- Possible reduced fuel economy (indirect)
- Diagnostic trouble codes related to O2 sensors or catalyst efficiency
What to check
- Scan for related codes and freeze frame data (confirm Bank 1 / Sensor 3 location)
- Visual inspection of sensor and harness for damage, corrosion, soot, or exhaust leaks
- Verify connector is fully seated and pins are clean and undamaged
- Check for signs of contamination on the sensor tip (soot, oil, coolant)
- Inspect nearby exhaust components and flange gaskets for leaks
- Check vehicle service information for sensor location and expected pinout
Signal parameters
- Typical narrow‑band O2 sensor signal (upstream) ~0.1–0.9 V (switching rapidly); downstream sensors usually more stable near ~0.4–0.6 V — values vary by vehicle
- P0142 often triggered when sensor signal is persistently very low (near 0.0–0.2 V) or circuit voltage is below expected threshold
- Heater circuit resistance (if equipped) commonly in the low ohm range — consult OEM spec for exact resistance
- Backprobe voltages: key on engine off — reference power ~5 V (if applicable) and heater supply ~12 V (if equipped) — check vehicle manual for correct values
Diagnostic algorithm
- Retrieve all DTCs and freeze frame, note conditions when code set; attempt to reproduce if safe
- Visually inspect sensor, connector and wiring for damage, corrosion, melted insulation or contamination; repair as needed
- Verify correct sensor identification (Bank 1 Sensor 3) using vehicle service data
- With connector connected, backprobe the signal wire and observe live data with a scan tool during key ON and engine running; note voltage behavior
- If circuit shows low voltage, check for short to ground: with ignition off measure continuity between signal wire and ground; no continuity expected
- Check for short to 12V: measure continuity between signal wire and battery positive; none expected
- Verify heater supply and ground (if sensor has heater): with key ON measure voltage at heater power pin and check heater resistance to ground against OEM spec
- Wiggle wiring harness while monitoring signal to detect intermittent shorts/open circuits
- Check for exhaust leaks upstream of the sensor and repair if present
- If wiring and power/grounds are good and connector pins check out, replace the sensor with a known good or OEM-equivalent unit
- After repair or replacement, clear codes and perform a drive cycle or readiness test to confirm the fault does not return
- If problems persist, consider ECM/PCM testing or replacement only after all wiring and sensors are verified good
Likely causes
- Damaged or corroded sensor connector/wiring causing low/grounded signal
- Failed sensor due to age/contamination
- Open or short in heater/power/ground circuit
- Exhaust leak or severe catalytic converter damage affecting sensor readings
Fault status
Status
O2 sensor circuit (Bank 1 Sensor 3) is reporting abnormally low voltage or abnormal operation. Inspect sensor, wiring, and related circuits.
Repair difficulty: Medium
Diagnostic time: 0.5–3 hours
Workshop Manuals
Available brands with manuals
2
AUDI 11
6-speed manual gearbox 0B1, front-wheel drive — Workshop Manual (Edition 05.2014)
Workshop ManualAudi A3 (1997) – 1.6L 4-cylinder (2‑valve) Engine Mechanical Components Service Manual (AEH, AKL, APF) – Edition 07.2002
Workshop ManualAUDI A3 (2004) Workshop Manual — 2.0L FSI Turbo (4‑cyl, 4‑valve) Engine, Mechanics — Edition 03.2017
Workshop ManualAudi A3 2004 — Electrical System (Workshop Manual, Edition 02.2018)
Workshop ManualAudi A4 / A4 Cabriolet – 4.2 l V8 (5‑valve, timing chains) – Workshop Manual (Mechanics) – Edition 04.2007
Workshop ManualAudi A4 / A4 Cabriolet — Auxiliary Heater Workshop Manual (Edition 08.2004)
Workshop ManualAudi A4 / A4 Cabriolet (1.8T 4‑cyl turbo) — Motronic Injection & Ignition System Service Manual (Edition 01.2015)
Workshop ManualAudi A8 (2003) — Electrical System Workshop Manual (Edition 08.2014)
Workshop ManualAudi Q4 e-tron (Type F4) - Self-study Programme SSP 685
Workshop ManualAudi Q8 (2018) — Electrical System Workshop Manual (Edition 05.2019)
Workshop ManualAudi Servicing Manual — 7‑Speed Dual Clutch Transmission 0CJ / 0CL / 0CK / 0DN / 0DP / 0HL (Edition 05.2018)
Workshop ManualLAND ROVER 3
Land Rover Defender 300Tdi — Workshop Manual (1996 model year)
Workshop ManualLand Rover Defender Workshop Manual Supplement & Body Repair Manual (1999 & 2002 MY)
Workshop ManualLand Rover Range Rover — Electrical Library (LRL 0453ENG, 2002)
Workshop ManualYour experience will help others
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Code
P0142
GWM
P — Powertrain
- O2 sensor circuit fault (bank 1, sensor 3)
Views:
UK: 1
EN: 3
RU: 1
AI status
Completed
Completed
100%
Causes
- Faulty O2 sensor (Bank 1 Sensor 3)
- Open, shorted or corroded sensor wiring or connector
- Poor ground or reference voltage to the sensor or heater circuit
- Exhaust leak upstream of the sensor
- Contaminated sensor (oil, coolant, silicone, leaded fuel)
- Failed PCM/ECM or internal driver fault
Symptoms
- Check Engine Light (MIL) on
- Failed emissions/inspection test
- Little or no noticeable drivability change in many vehicles
- Possible reduced fuel economy (indirect)
- Diagnostic trouble codes related to O2 sensors or catalyst efficiency
What to check
- Scan for related codes and freeze frame data (confirm Bank 1 / Sensor 3 location)
- Visual inspection of sensor and harness for damage, corrosion, soot, or exhaust leaks
- Verify connector is fully seated and pins are clean and undamaged
- Check for signs of contamination on the sensor tip (soot, oil, coolant)
- Inspect nearby exhaust components and flange gaskets for leaks
- Check vehicle service information for sensor location and expected pinout
Signal parameters
- Typical narrow‑band O2 sensor signal (upstream) ~0.1–0.9 V (switching rapidly); downstream sensors usually more stable near ~0.4–0.6 V — values vary by vehicle
- P0142 often triggered when sensor signal is persistently very low (near 0.0–0.2 V) or circuit voltage is below expected threshold
- Heater circuit resistance (if equipped) commonly in the low ohm range — consult OEM spec for exact resistance
- Backprobe voltages: key on engine off — reference power ~5 V (if applicable) and heater supply ~12 V (if equipped) — check vehicle manual for correct values
Diagnostic algorithm
- Retrieve all DTCs and freeze frame, note conditions when code set; attempt to reproduce if safe
- Visually inspect sensor, connector and wiring for damage, corrosion, melted insulation or contamination; repair as needed
- Verify correct sensor identification (Bank 1 Sensor 3) using vehicle service data
- With connector connected, backprobe the signal wire and observe live data with a scan tool during key ON and engine running; note voltage behavior
- If circuit shows low voltage, check for short to ground: with ignition off measure continuity between signal wire and ground; no continuity expected
- Check for short to 12V: measure continuity between signal wire and battery positive; none expected
- Verify heater supply and ground (if sensor has heater): with key ON measure voltage at heater power pin and check heater resistance to ground against OEM spec
- Wiggle wiring harness while monitoring signal to detect intermittent shorts/open circuits
- Check for exhaust leaks upstream of the sensor and repair if present
- If wiring and power/grounds are good and connector pins check out, replace the sensor with a known good or OEM-equivalent unit
- After repair or replacement, clear codes and perform a drive cycle or readiness test to confirm the fault does not return
- If problems persist, consider ECM/PCM testing or replacement only after all wiring and sensors are verified good
Likely causes
- Damaged or corroded sensor connector/wiring causing low/grounded signal
- Failed sensor due to age/contamination
- Open or short in heater/power/ground circuit
- Exhaust leak or severe catalytic converter damage affecting sensor readings
Fault status
Status
O2 sensor circuit (Bank 1 Sensor 3) is reporting abnormally low voltage or abnormal operation. Inspect sensor, wiring, and related circuits.
Repair difficulty: Medium
Diagnostic time: 0.5–3 hours
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Code
P0142
HUMMER
P — Powertrain
Heated Oxygen Sensor (HO2S) Circuit Bank 1 Sensor 3
Views:
UK: 7
EN: 11
RU: 9
AI status
Completed
Completed
100%
Causes
- Faulty O2 sensor (Bank 1 Sensor 3)
- Open, shorted or corroded sensor wiring or connector
- Poor ground or reference voltage to the sensor or heater circuit
- Exhaust leak upstream of the sensor
- Contaminated sensor (oil, coolant, silicone, leaded fuel)
- Failed PCM/ECM or internal driver fault
Symptoms
- Check Engine Light (MIL) on
- Failed emissions/inspection test
- Little or no noticeable drivability change in many vehicles
- Possible reduced fuel economy (indirect)
- Diagnostic trouble codes related to O2 sensors or catalyst efficiency
What to check
- Scan for related codes and freeze frame data (confirm Bank 1 / Sensor 3 location)
- Visual inspection of sensor and harness for damage, corrosion, soot, or exhaust leaks
- Verify connector is fully seated and pins are clean and undamaged
- Check for signs of contamination on the sensor tip (soot, oil, coolant)
- Inspect nearby exhaust components and flange gaskets for leaks
- Check vehicle service information for sensor location and expected pinout
Signal parameters
- Typical narrow‑band O2 sensor signal (upstream) ~0.1–0.9 V (switching rapidly); downstream sensors usually more stable near ~0.4–0.6 V — values vary by vehicle
- P0142 often triggered when sensor signal is persistently very low (near 0.0–0.2 V) or circuit voltage is below expected threshold
- Heater circuit resistance (if equipped) commonly in the low ohm range — consult OEM spec for exact resistance
- Backprobe voltages: key on engine off — reference power ~5 V (if applicable) and heater supply ~12 V (if equipped) — check vehicle manual for correct values
Diagnostic algorithm
- Retrieve all DTCs and freeze frame, note conditions when code set; attempt to reproduce if safe
- Visually inspect sensor, connector and wiring for damage, corrosion, melted insulation or contamination; repair as needed
- Verify correct sensor identification (Bank 1 Sensor 3) using vehicle service data
- With connector connected, backprobe the signal wire and observe live data with a scan tool during key ON and engine running; note voltage behavior
- If circuit shows low voltage, check for short to ground: with ignition off measure continuity between signal wire and ground; no continuity expected
- Check for short to 12V: measure continuity between signal wire and battery positive; none expected
- Verify heater supply and ground (if sensor has heater): with key ON measure voltage at heater power pin and check heater resistance to ground against OEM spec
- Wiggle wiring harness while monitoring signal to detect intermittent shorts/open circuits
- Check for exhaust leaks upstream of the sensor and repair if present
- If wiring and power/grounds are good and connector pins check out, replace the sensor with a known good or OEM-equivalent unit
- After repair or replacement, clear codes and perform a drive cycle or readiness test to confirm the fault does not return
- If problems persist, consider ECM/PCM testing or replacement only after all wiring and sensors are verified good
Likely causes
- Damaged or corroded sensor connector/wiring causing low/grounded signal
- Failed sensor due to age/contamination
- Open or short in heater/power/ground circuit
- Exhaust leak or severe catalytic converter damage affecting sensor readings
Fault status
Status
O2 sensor circuit (Bank 1 Sensor 3) is reporting abnormally low voltage or abnormal operation. Inspect sensor, wiring, and related circuits.
Repair difficulty: Medium
Diagnostic time: 0.5–3 hours
Your experience will help others
+100 karma for a short comment :)
Was this AI description helpful?
Your feedback helps improve AI descriptions.
👍 Like
0
👎 Dislike
0
Send to email
Code
P0142
LAND ROVER
P — Powertrain
Oxygen sensor circuit. Bank 1 - sensor 3
Views:
UK: 2
EN: 8
RU: 5
AI status
Completed
Completed
100%
Causes
- Faulty O2 sensor (Bank 1 Sensor 3)
- Open, shorted or corroded sensor wiring or connector
- Poor ground or reference voltage to the sensor or heater circuit
- Exhaust leak upstream of the sensor
- Contaminated sensor (oil, coolant, silicone, leaded fuel)
- Failed PCM/ECM or internal driver fault
Symptoms
- Check Engine Light (MIL) on
- Failed emissions/inspection test
- Little or no noticeable drivability change in many vehicles
- Possible reduced fuel economy (indirect)
- Diagnostic trouble codes related to O2 sensors or catalyst efficiency
What to check
- Scan for related codes and freeze frame data (confirm Bank 1 / Sensor 3 location)
- Visual inspection of sensor and harness for damage, corrosion, soot, or exhaust leaks
- Verify connector is fully seated and pins are clean and undamaged
- Check for signs of contamination on the sensor tip (soot, oil, coolant)
- Inspect nearby exhaust components and flange gaskets for leaks
- Check vehicle service information for sensor location and expected pinout
Signal parameters
- Typical narrow‑band O2 sensor signal (upstream) ~0.1–0.9 V (switching rapidly); downstream sensors usually more stable near ~0.4–0.6 V — values vary by vehicle
- P0142 often triggered when sensor signal is persistently very low (near 0.0–0.2 V) or circuit voltage is below expected threshold
- Heater circuit resistance (if equipped) commonly in the low ohm range — consult OEM spec for exact resistance
- Backprobe voltages: key on engine off — reference power ~5 V (if applicable) and heater supply ~12 V (if equipped) — check vehicle manual for correct values
Diagnostic algorithm
- Retrieve all DTCs and freeze frame, note conditions when code set; attempt to reproduce if safe
- Visually inspect sensor, connector and wiring for damage, corrosion, melted insulation or contamination; repair as needed
- Verify correct sensor identification (Bank 1 Sensor 3) using vehicle service data
- With connector connected, backprobe the signal wire and observe live data with a scan tool during key ON and engine running; note voltage behavior
- If circuit shows low voltage, check for short to ground: with ignition off measure continuity between signal wire and ground; no continuity expected
- Check for short to 12V: measure continuity between signal wire and battery positive; none expected
- Verify heater supply and ground (if sensor has heater): with key ON measure voltage at heater power pin and check heater resistance to ground against OEM spec
- Wiggle wiring harness while monitoring signal to detect intermittent shorts/open circuits
- Check for exhaust leaks upstream of the sensor and repair if present
- If wiring and power/grounds are good and connector pins check out, replace the sensor with a known good or OEM-equivalent unit
- After repair or replacement, clear codes and perform a drive cycle or readiness test to confirm the fault does not return
- If problems persist, consider ECM/PCM testing or replacement only after all wiring and sensors are verified good
Likely causes
- Damaged or corroded sensor connector/wiring causing low/grounded signal
- Failed sensor due to age/contamination
- Open or short in heater/power/ground circuit
- Exhaust leak or severe catalytic converter damage affecting sensor readings
Fault status
Status
O2 sensor circuit (Bank 1 Sensor 3) is reporting abnormally low voltage or abnormal operation. Inspect sensor, wiring, and related circuits.
Repair difficulty: Medium
Diagnostic time: 0.5–3 hours
Workshop Manuals
Repair manuals for LAND ROVER
3
Land Rover Defender 300Tdi — Workshop Manual (1996 model year)
Workshop ManualLand Rover Defender Workshop Manual Supplement & Body Repair Manual (1999 & 2002 MY)
Workshop ManualLand Rover Range Rover — Electrical Library (LRL 0453ENG, 2002)
Workshop ManualYour experience will help others
+100 karma for a short comment :)
Was this AI description helpful?
Your feedback helps improve AI descriptions.
👍 Like
0
👎 Dislike
0
Send to email