Code
P0426
Generic
P — Powertrain
Catalyst Temperature Sensor Circuit Range/Performance Bank 1 Sensor 1
Views:
UK: 24
EN: 37
RU: 39
AI status
Completed
Completed
100%
Causes
- Faulty catalyst/exhaust temperature sensor (Bank 1, Sensor 1)
- Damaged or corroded wiring/connector to the sensor
- Open or short in sensor heater circuit (if equipped)
- Exhaust leak upstream of the sensor affecting readings
- Failed sensor ground or reference circuit
- Intermittent connection or water intrusion in connector
Symptoms
- Malfunction Indicator Lamp (MIL) / CEL illuminated
- Failed emissions test or readiness failed
- Possible reduced engine performance or active emission-related limp mode (rare)
- Unusual exhaust odor or visible smoke if catalytic issues exist
- Poor fuel economy if ECM enters open-loop or alters fueling
What to check
- Retrieve freeze frame and live data with a scan tool; record freeze-frame parameters
- Verify stored/freeze-frame conditions: engine temp, vehicle speed, load, fuel trim
- Visually inspect sensor and connector for damage, corrosion, oil or soot contamination
- Check for exhaust leaks upstream of the sensor (loose manifold bolts, gaskets)
- Backprobe sensor signal and ground with scan tool connected; observe voltage/temperature values at key on and during warm-up
- Check sensor heater supply and ground (if equipped) for proper voltage/resistance
Signal parameters
- Sensor type: typically a temperature sensor (thermistor or thermocouple) placed in exhaust stream before the catalyst
- Typical signal range: 0–5 V (depends on vehicle/ECM); expected change in voltage/temperature correlates with exhaust temperature
- Heater circuit (if present): has battery voltage feed and switched ground/drive from ECM; heater resistance varies by design
- Expected behavior: rapid rise in reported temperature after engine start as exhaust warms; values should be consistent with downstream sensor trends and with engine load
- Compare Bank 1 Sensor 1 to Bank 1 Sensor 2 (downstream) and to expected warm-up profile in manufacturer data
Diagnostic algorithm
- Confirm code and capture freeze-frame/live data with a capable scan tool. Note engine temperature, rpm, load, and sensor temperature readings at fault occurrence.
- Visually inspect Bank 1 Sensor 1 and harness. Look for heat damage, soot, oil, broken wires, or corrosion. Repair any obvious wiring/connector damage.
- Check for exhaust leaks upstream of the sensor; repair any leaks and retest.
- With ignition ON (engine OFF), backprobe the sensor connector: verify reference voltage/ground presence per manufacturer data. If heater-equipped, verify battery feed to heater circuit.
- Start engine and monitor sensor voltage/temperature. Observe response during warm-up and under varying loads. Compare readings to downstream sensor and to expected behavior. Look for stuck, out-of-range, or no-change values.
- Measure sensor element resistance (if thermistor type) cold and after warming (do not remove sensor from hot exhaust). Compare to spec if available. Replace if out of range.
- Perform wiggle test on harness/connectors while observing data to find intermittent faults.
- If heater circuit is suspected, measure heater resistance and activation. Check ECM driver circuit for switching and for shorts to power/ground.
- If wiring and heater are good, substitute a known-good sensor or install a new sensor and clear codes to see if code returns.
- If problem persists after sensor replacement and wiring verified, test or reflash ECM input circuit per manufacturer procedures or consult dealer-level diagnostics.
Likely causes
- Sensor degraded (thermistor or thermocouple element out of spec)
- Connector pins corroded or pushed out
- Wire chafing causing intermittent short to ground or voltage
- Failed sensor heater (common on heated exhaust temp sensors)
- Exhaust leak between head and sensor causing false low/high readings
Fault status
Status
Catalyst/exhaust temperature sensor (Bank 1 Sensor 1) circuit response is out of expected range or performance; ECM flagged as failing diagnostic criteria.
Repair difficulty: Medium
Diagnostic time: 1.0-2.5 hours
Similar codes
Repair manuals
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Code
P0426
ISUZU
P — Powertrain
Catalyst Temperature Sensor Circuit Range/Performance Sensor 1
Views:
UK: 23
EN: 40
RU: 30
AI status
Completed
Completed
100%
Causes
- Faulty catalyst/exhaust temperature sensor (Bank 1, Sensor 1)
- Damaged or corroded wiring/connector to the sensor
- Open or short in sensor heater circuit (if equipped)
- Exhaust leak upstream of the sensor affecting readings
- Failed sensor ground or reference circuit
- Intermittent connection or water intrusion in connector
Symptoms
- Malfunction Indicator Lamp (MIL) / CEL illuminated
- Failed emissions test or readiness failed
- Possible reduced engine performance or active emission-related limp mode (rare)
- Unusual exhaust odor or visible smoke if catalytic issues exist
- Poor fuel economy if ECM enters open-loop or alters fueling
What to check
- Retrieve freeze frame and live data with a scan tool; record freeze-frame parameters
- Verify stored/freeze-frame conditions: engine temp, vehicle speed, load, fuel trim
- Visually inspect sensor and connector for damage, corrosion, oil or soot contamination
- Check for exhaust leaks upstream of the sensor (loose manifold bolts, gaskets)
- Backprobe sensor signal and ground with scan tool connected; observe voltage/temperature values at key on and during warm-up
- Check sensor heater supply and ground (if equipped) for proper voltage/resistance
Signal parameters
- Sensor type: typically a temperature sensor (thermistor or thermocouple) placed in exhaust stream before the catalyst
- Typical signal range: 0–5 V (depends on vehicle/ECM); expected change in voltage/temperature correlates with exhaust temperature
- Heater circuit (if present): has battery voltage feed and switched ground/drive from ECM; heater resistance varies by design
- Expected behavior: rapid rise in reported temperature after engine start as exhaust warms; values should be consistent with downstream sensor trends and with engine load
- Compare Bank 1 Sensor 1 to Bank 1 Sensor 2 (downstream) and to expected warm-up profile in manufacturer data
Diagnostic algorithm
- Confirm code and capture freeze-frame/live data with a capable scan tool. Note engine temperature, rpm, load, and sensor temperature readings at fault occurrence.
- Visually inspect Bank 1 Sensor 1 and harness. Look for heat damage, soot, oil, broken wires, or corrosion. Repair any obvious wiring/connector damage.
- Check for exhaust leaks upstream of the sensor; repair any leaks and retest.
- With ignition ON (engine OFF), backprobe the sensor connector: verify reference voltage/ground presence per manufacturer data. If heater-equipped, verify battery feed to heater circuit.
- Start engine and monitor sensor voltage/temperature. Observe response during warm-up and under varying loads. Compare readings to downstream sensor and to expected behavior. Look for stuck, out-of-range, or no-change values.
- Measure sensor element resistance (if thermistor type) cold and after warming (do not remove sensor from hot exhaust). Compare to spec if available. Replace if out of range.
- Perform wiggle test on harness/connectors while observing data to find intermittent faults.
- If heater circuit is suspected, measure heater resistance and activation. Check ECM driver circuit for switching and for shorts to power/ground.
- If wiring and heater are good, substitute a known-good sensor or install a new sensor and clear codes to see if code returns.
- If problem persists after sensor replacement and wiring verified, test or reflash ECM input circuit per manufacturer procedures or consult dealer-level diagnostics.
Likely causes
- Sensor degraded (thermistor or thermocouple element out of spec)
- Connector pins corroded or pushed out
- Wire chafing causing intermittent short to ground or voltage
- Failed sensor heater (common on heated exhaust temp sensors)
- Exhaust leak between head and sensor causing false low/high readings
Fault status
Status
Catalyst/exhaust temperature sensor (Bank 1 Sensor 1) circuit response is out of expected range or performance; ECM flagged as failing diagnostic criteria.
Repair difficulty: Medium
Diagnostic time: 1.0-2.5 hours
Similar codes
Repair manuals
Manual library for ISUZU
43
Browse 43 ISUZU manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.
ISUZU
-
ISUZU: 2008
-
ISUZU: 2007
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Code
P0426
LAND ROVER
P — Powertrain
Range / performance of catalyst temperature sensor (bank 1)
Views:
UK: 17
EN: 31
RU: 33
AI status
Completed
Completed
100%
Causes
- Faulty catalyst/exhaust temperature sensor (Bank 1, Sensor 1)
- Damaged or corroded wiring/connector to the sensor
- Open or short in sensor heater circuit (if equipped)
- Exhaust leak upstream of the sensor affecting readings
- Failed sensor ground or reference circuit
- Intermittent connection or water intrusion in connector
Symptoms
- Malfunction Indicator Lamp (MIL) / CEL illuminated
- Failed emissions test or readiness failed
- Possible reduced engine performance or active emission-related limp mode (rare)
- Unusual exhaust odor or visible smoke if catalytic issues exist
- Poor fuel economy if ECM enters open-loop or alters fueling
What to check
- Retrieve freeze frame and live data with a scan tool; record freeze-frame parameters
- Verify stored/freeze-frame conditions: engine temp, vehicle speed, load, fuel trim
- Visually inspect sensor and connector for damage, corrosion, oil or soot contamination
- Check for exhaust leaks upstream of the sensor (loose manifold bolts, gaskets)
- Backprobe sensor signal and ground with scan tool connected; observe voltage/temperature values at key on and during warm-up
- Check sensor heater supply and ground (if equipped) for proper voltage/resistance
Signal parameters
- Sensor type: typically a temperature sensor (thermistor or thermocouple) placed in exhaust stream before the catalyst
- Typical signal range: 0–5 V (depends on vehicle/ECM); expected change in voltage/temperature correlates with exhaust temperature
- Heater circuit (if present): has battery voltage feed and switched ground/drive from ECM; heater resistance varies by design
- Expected behavior: rapid rise in reported temperature after engine start as exhaust warms; values should be consistent with downstream sensor trends and with engine load
- Compare Bank 1 Sensor 1 to Bank 1 Sensor 2 (downstream) and to expected warm-up profile in manufacturer data
Diagnostic algorithm
- Confirm code and capture freeze-frame/live data with a capable scan tool. Note engine temperature, rpm, load, and sensor temperature readings at fault occurrence.
- Visually inspect Bank 1 Sensor 1 and harness. Look for heat damage, soot, oil, broken wires, or corrosion. Repair any obvious wiring/connector damage.
- Check for exhaust leaks upstream of the sensor; repair any leaks and retest.
- With ignition ON (engine OFF), backprobe the sensor connector: verify reference voltage/ground presence per manufacturer data. If heater-equipped, verify battery feed to heater circuit.
- Start engine and monitor sensor voltage/temperature. Observe response during warm-up and under varying loads. Compare readings to downstream sensor and to expected behavior. Look for stuck, out-of-range, or no-change values.
- Measure sensor element resistance (if thermistor type) cold and after warming (do not remove sensor from hot exhaust). Compare to spec if available. Replace if out of range.
- Perform wiggle test on harness/connectors while observing data to find intermittent faults.
- If heater circuit is suspected, measure heater resistance and activation. Check ECM driver circuit for switching and for shorts to power/ground.
- If wiring and heater are good, substitute a known-good sensor or install a new sensor and clear codes to see if code returns.
- If problem persists after sensor replacement and wiring verified, test or reflash ECM input circuit per manufacturer procedures or consult dealer-level diagnostics.
Likely causes
- Sensor degraded (thermistor or thermocouple element out of spec)
- Connector pins corroded or pushed out
- Wire chafing causing intermittent short to ground or voltage
- Failed sensor heater (common on heated exhaust temp sensors)
- Exhaust leak between head and sensor causing false low/high readings
Fault status
Status
Catalyst/exhaust temperature sensor (Bank 1 Sensor 1) circuit response is out of expected range or performance; ECM flagged as failing diagnostic criteria.
Repair difficulty: Medium
Diagnostic time: 1.0-2.5 hours
Similar codes
Repair manuals
Manual library for LAND ROVER
160
Browse 160 LAND ROVER manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.
LAND ROVER
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LAND ROVER: 2023
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Range Rover Velar
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LAND ROVER: 2022
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Discovery Sport
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Range Rover
- Autobiography, 4.4L Eng VIN 7 · 4.4L Eng VIN 72022: Range Rover Autobiography
- Autobiography, 5.0L Eng VIN E · 5.0L Eng VIN E2022: Range Rover Autobiography
- 2022 Range Rover Base
- First Edition
- HSE Westminster, 3.0L Eng VIN U · 3.0L Eng VIN U2022: Range Rover HSE Westminster
- HSE Westminster, 5.0L Eng VIN E · 5.0L Eng VIN E2022: Range Rover HSE Westminster
- SE, 3.0L Eng VIN U · 3.0L Eng VIN U2022: Range Rover SE
- SE, 4.4L Eng VIN 7 · 4.4L Eng VIN 72022: Range Rover SE
- SV
- SVAutobiography
- SVAutobiography Dynamic
- SVAutobiography Dynamic Blk.
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Range Rover Evoque
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Range Rover Sport
-
Range Rover Velar
-
LAND ROVER: 2021
-
Discovery Sport
-
Range Rover
- Autobiography, 2.0L Eng VIN Y · 2.0L Eng VIN Y2021: Range Rover Autobiography
- Autobiography Fifty Edition
- 2021 Range Rover Base
- HSE, 2.0L Eng VIN Y · 2.0L Eng VIN Y2021: Range Rover HSE
- HSE, 3.0L Eng VIN K · 3.0L Eng VIN K2021: Range Rover HSE
- HSE Westminster, 3.0L Eng VIN U · 3.0L Eng VIN U2021: Range Rover HSE Westminster
- HSE Westminster, 5.0L Eng VIN E · 5.0L Eng VIN E2021: Range Rover HSE Westminster
- SVAutobiography
- SVAutobiography Dynamic
- SVAutobiography Dynamic Blk.
-
Range Rover Evoque
-
Range Rover Sport
- Autobiography, 2.0L Eng VIN Y · 2.0L Eng VIN Y2021: Range Rover Sport Autobiography
- Autobiography, 5.0L Eng VIN E · 5.0L Eng VIN E2021: Range Rover Sport Autobiography
- Autobiography Dynamic, 2.0L Eng VIN Y · 2.0L Eng VIN Y2021: Range Rover Sport Autobiography Dynamic
- Autobiography Dynamic, 5.0L Eng VIN E · 5.0L Eng VIN E2021: Range Rover Sport Autobiography Dynamic
- HSE Dynamic
- HSE Silver Edition, 2.0L Eng VIN Y · 2.0L Eng VIN Y2021: Range Rover Sport HSE Silver Edition
- HSE Silver Edition, 3.0L Eng VIN K · 3.0L Eng VIN K2021: Range Rover Sport HSE Silver Edition
- HSE Silver Edition, 3.0L Eng VIN U · 3.0L Eng VIN U2021: Range Rover Sport HSE Silver Edition
- HST
- SE
- SVR
- SVR Carbon Edition
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Range Rover Velar
-
LAND ROVER: 2020
-
Discovery
- HSE, 3.0L Eng VIN K · 3.0L Eng VIN K2020: Discovery HSE
- HSE, 3.0L Eng VIN V · 3.0L Eng VIN V2020: Discovery HSE
- HSE Luxury, 3.0L Eng VIN K · 3.0L Eng VIN K2020: Discovery HSE Luxury
- HSE Luxury, 3.0L Eng VIN V · 3.0L Eng VIN V2020: Discovery HSE Luxury
- Landmark
- SE, 3.0L Eng VIN K · 3.0L Eng VIN K2020: Discovery SE
- SE, 3.0L Eng VIN V · 3.0L Eng VIN V2020: Discovery SE
-
Discovery Sport
-
Range Rover
- Autobiography
- Base, 3.0L Eng VIN K · 3.0L Eng VIN K2020: Range Rover Base
- Base, 3.0L Eng VIN U · 3.0L Eng VIN U2020: Range Rover Base
- HSE, 2.0L Eng VIN Y · 2.0L Eng VIN Y2020: Range Rover HSE
- HSE, 3.0L Eng VIN K · 3.0L Eng VIN K2020: Range Rover HSE
- HSE, 3.0L Eng VIN U · 3.0L Eng VIN U2020: Range Rover HSE
- HSE, 5.0L Eng VIN E · 5.0L Eng VIN E2020: Range Rover HSE
- SVAutobiography
- SVAutobiography Dynamic
-
Range Rover Evoque
-
Range Rover Sport
- Autobiography Dynamic, 2.0L Eng VIN Y · 2.0L Eng VIN Y2020: Range Rover Sport Autobiography Dynamic
- Autobiography Dynamic, 5.0L Eng VIN E · 5.0L Eng VIN E2020: Range Rover Sport Autobiography Dynamic
- HSE, 3.0L Eng VIN K · 3.0L Eng VIN K2020: Range Rover Sport HSE
- HSE, 3.0L Eng VIN U · 3.0L Eng VIN U2020: Range Rover Sport HSE
- HSE, 5.0L Eng VIN E · 5.0L Eng VIN E2020: Range Rover Sport HSE
- HSE Dynamic
- HSE PHEV
- HST
- SE, 3.0L Eng VIN K · 3.0L Eng VIN K2020: Range Rover Sport SE
- SE, 3.0L Eng VIN U · 3.0L Eng VIN U2020: Range Rover Sport SE
- SVR
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Range Rover Velar
- R-Dynamic HSE
- R-Dynamic S, 2.0L Eng VIN X · 2.0L Eng VIN X2020: Range Rover Velar R-Dynamic S
- R-Dynamic S, 3.0L Eng VIN V · 3.0L Eng VIN V2020: Range Rover Velar R-Dynamic S
- S, 2.0L Eng VIN X · 2.0L Eng VIN X2020: Range Rover Velar S
- S, 3.0L Eng VIN V · 3.0L Eng VIN V2020: Range Rover Velar S
- SVAutobiography Dyn.
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LAND ROVER: 2019
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