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Home / DTC / P0133 — O2 Sensor Circuit Slow Response Bank 1 Sensor 1

P0133 — O2 Sensor Circuit Slow Response Bank 1 Sensor 1

Detailed page for trouble code P0133.

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Code

P0133

Generic P — Powertrain

O2 Sensor Circuit Slow Response Bank 1 Sensor 1

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

Causes

  • Aging or contaminated upstream O2 sensor (slow to switch)
  • Wiring harness damage, corroded connector, or poor ground to the sensor
  • Exhaust leak upstream of the sensor affecting readings
  • Fuel system or ignition issues causing unstable/abnormal switching (rich/lean events, misfire)
  • Faulty sensor heater (sensor not reaching operating temperature quickly)
  • Excessive exhaust backpressure or catalytic converter problem affecting sensor readings

Symptoms

  • Check Engine Light (MIL) illuminated
  • Poor fuel economy
  • Rough idle or hesitation during acceleration
  • Higher than normal emissions (failed inspection)
  • Delayed O2 voltage switching on live data during snap-throttle tests

What to check

  • Read and record freeze frame and pending codes; verify P0133 is current and reproducible
  • Scan live O2 sensor voltage (Bank 1 Sensor 1) at operating temp; observe switching behavior during steady state and snap-throttle
  • Check short-term and long-term fuel trims for abnormal values
  • Visually inspect sensor, connector, and wiring for damage, corrosion, heat damage, or oil/coolant contamination
  • Check for exhaust leaks upstream of the sensor (listen, use smoke or soapy water if safe)
  • Measure heater circuit resistance and supply voltage (if sensor has heater) with connector disconnected — compare to spec

Signal parameters

  • Typical narrowband upstream O2 voltage range: ~0.1 V (lean) to ~0.9 V (rich)
  • Healthy sensor should switch rapidly (several times per second) between lean and rich under steady operating conditions; response time typically measured in tens to low hundreds of milliseconds (manufacturer-specific)
  • Slow-response symptom: delayed voltage transition when air/fuel is changed or after snap throttle
  • Heater circuit: expected supply ≈ battery voltage when commanded; heater resistance is usually low (consult vehicle spec)

Diagnostic algorithm

  1. Verify the code: clear the code, drive or re-run readiness checks to see if P0133 returns and capture freeze-frame data.
  2. Monitor live data: warm the engine to normal operating temperature and observe Bank 1 Sensor 1 voltage. Perform snap-throttle or induced lean/rich events (introduce vacuum leak briefly or tap throttle) to see if the sensor switches quickly. Compare with Bank 2 Sensor 1 if present.
  3. Check fuel trims: if long-term short-term fuel trims are extreme, diagnose underlying fuel/ignition issues (fuel pressure, injectors, misfire, vacuum leaks) before replacing the sensor.
  4. Inspect wiring/connectors: unplug connector, inspect pins for corrosion, bent pins, or water ingress. Backprobe and check for proper reference voltage and ground while monitoring sensor signal.
  5. Test heater circuit: with connector disconnected measure heater resistance and verify power/ground when the engine/ignition commanded. Replace sensor if heater is open or out of spec.
  6. Test response electrically: with scope or scan tool record the voltage waveform during transient conditions. If waveform is sluggish (slow rise/fall) and wiring/power/ground are good, the sensor is likely defective.
  7. Check for exhaust leaks upstream of sensor and repair if present, then retest.
  8. Repair wiring or connector faults found. If wiring and engine systems are good and sensor is old or contaminated, replace the Bank 1 Sensor 1 with OE-equivalent sensor.
  9. After repairs clear codes and confirm proper operation over driving cycles and that the code does not return.

Likely causes

  • Worn/contaminated sensor (most common with age/high mileage)
  • Damaged or corroded connector or wiring (intermittent/slow signal)
  • Exhaust leak between cylinder head and sensor
  • Long-term fuel trim or injection problem creating poor sensor switching

Fault status

⚠️ Status
Bank 1 Sensor 1 O2 sensor response is slower than expected; possible slow-switching sensor, wiring problem, or upstream condition affecting readings.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1.0-2.5 hours
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Code

P0133

GWM P — Powertrain

- The oxygen sensor responds late (bank 1, sensor 1)

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

Causes

  • Aging or contaminated upstream O2 sensor (slow to switch)
  • Wiring harness damage, corroded connector, or poor ground to the sensor
  • Exhaust leak upstream of the sensor affecting readings
  • Fuel system or ignition issues causing unstable/abnormal switching (rich/lean events, misfire)
  • Faulty sensor heater (sensor not reaching operating temperature quickly)
  • Excessive exhaust backpressure or catalytic converter problem affecting sensor readings

Symptoms

  • Check Engine Light (MIL) illuminated
  • Poor fuel economy
  • Rough idle or hesitation during acceleration
  • Higher than normal emissions (failed inspection)
  • Delayed O2 voltage switching on live data during snap-throttle tests

What to check

  • Read and record freeze frame and pending codes; verify P0133 is current and reproducible
  • Scan live O2 sensor voltage (Bank 1 Sensor 1) at operating temp; observe switching behavior during steady state and snap-throttle
  • Check short-term and long-term fuel trims for abnormal values
  • Visually inspect sensor, connector, and wiring for damage, corrosion, heat damage, or oil/coolant contamination
  • Check for exhaust leaks upstream of the sensor (listen, use smoke or soapy water if safe)
  • Measure heater circuit resistance and supply voltage (if sensor has heater) with connector disconnected — compare to spec

Signal parameters

  • Typical narrowband upstream O2 voltage range: ~0.1 V (lean) to ~0.9 V (rich)
  • Healthy sensor should switch rapidly (several times per second) between lean and rich under steady operating conditions; response time typically measured in tens to low hundreds of milliseconds (manufacturer-specific)
  • Slow-response symptom: delayed voltage transition when air/fuel is changed or after snap throttle
  • Heater circuit: expected supply ≈ battery voltage when commanded; heater resistance is usually low (consult vehicle spec)

Diagnostic algorithm

  1. Verify the code: clear the code, drive or re-run readiness checks to see if P0133 returns and capture freeze-frame data.
  2. Monitor live data: warm the engine to normal operating temperature and observe Bank 1 Sensor 1 voltage. Perform snap-throttle or induced lean/rich events (introduce vacuum leak briefly or tap throttle) to see if the sensor switches quickly. Compare with Bank 2 Sensor 1 if present.
  3. Check fuel trims: if long-term short-term fuel trims are extreme, diagnose underlying fuel/ignition issues (fuel pressure, injectors, misfire, vacuum leaks) before replacing the sensor.
  4. Inspect wiring/connectors: unplug connector, inspect pins for corrosion, bent pins, or water ingress. Backprobe and check for proper reference voltage and ground while monitoring sensor signal.
  5. Test heater circuit: with connector disconnected measure heater resistance and verify power/ground when the engine/ignition commanded. Replace sensor if heater is open or out of spec.
  6. Test response electrically: with scope or scan tool record the voltage waveform during transient conditions. If waveform is sluggish (slow rise/fall) and wiring/power/ground are good, the sensor is likely defective.
  7. Check for exhaust leaks upstream of sensor and repair if present, then retest.
  8. Repair wiring or connector faults found. If wiring and engine systems are good and sensor is old or contaminated, replace the Bank 1 Sensor 1 with OE-equivalent sensor.
  9. After repairs clear codes and confirm proper operation over driving cycles and that the code does not return.

Likely causes

  • Worn/contaminated sensor (most common with age/high mileage)
  • Damaged or corroded connector or wiring (intermittent/slow signal)
  • Exhaust leak between cylinder head and sensor
  • Long-term fuel trim or injection problem creating poor sensor switching

Fault status

⚠️ Status
Bank 1 Sensor 1 O2 sensor response is slower than expected; possible slow-switching sensor, wiring problem, or upstream condition affecting readings.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1.0-2.5 hours
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Code

P0133

HUMMER P — Powertrain

Heated Oxygen Sensor (HO2S) Slow Response Bank 1 Sensor 1

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

Causes

  • Aging or contaminated upstream O2 sensor (slow to switch)
  • Wiring harness damage, corroded connector, or poor ground to the sensor
  • Exhaust leak upstream of the sensor affecting readings
  • Fuel system or ignition issues causing unstable/abnormal switching (rich/lean events, misfire)
  • Faulty sensor heater (sensor not reaching operating temperature quickly)
  • Excessive exhaust backpressure or catalytic converter problem affecting sensor readings

Symptoms

  • Check Engine Light (MIL) illuminated
  • Poor fuel economy
  • Rough idle or hesitation during acceleration
  • Higher than normal emissions (failed inspection)
  • Delayed O2 voltage switching on live data during snap-throttle tests

What to check

  • Read and record freeze frame and pending codes; verify P0133 is current and reproducible
  • Scan live O2 sensor voltage (Bank 1 Sensor 1) at operating temp; observe switching behavior during steady state and snap-throttle
  • Check short-term and long-term fuel trims for abnormal values
  • Visually inspect sensor, connector, and wiring for damage, corrosion, heat damage, or oil/coolant contamination
  • Check for exhaust leaks upstream of the sensor (listen, use smoke or soapy water if safe)
  • Measure heater circuit resistance and supply voltage (if sensor has heater) with connector disconnected — compare to spec

Signal parameters

  • Typical narrowband upstream O2 voltage range: ~0.1 V (lean) to ~0.9 V (rich)
  • Healthy sensor should switch rapidly (several times per second) between lean and rich under steady operating conditions; response time typically measured in tens to low hundreds of milliseconds (manufacturer-specific)
  • Slow-response symptom: delayed voltage transition when air/fuel is changed or after snap throttle
  • Heater circuit: expected supply ≈ battery voltage when commanded; heater resistance is usually low (consult vehicle spec)

Diagnostic algorithm

  1. Verify the code: clear the code, drive or re-run readiness checks to see if P0133 returns and capture freeze-frame data.
  2. Monitor live data: warm the engine to normal operating temperature and observe Bank 1 Sensor 1 voltage. Perform snap-throttle or induced lean/rich events (introduce vacuum leak briefly or tap throttle) to see if the sensor switches quickly. Compare with Bank 2 Sensor 1 if present.
  3. Check fuel trims: if long-term short-term fuel trims are extreme, diagnose underlying fuel/ignition issues (fuel pressure, injectors, misfire, vacuum leaks) before replacing the sensor.
  4. Inspect wiring/connectors: unplug connector, inspect pins for corrosion, bent pins, or water ingress. Backprobe and check for proper reference voltage and ground while monitoring sensor signal.
  5. Test heater circuit: with connector disconnected measure heater resistance and verify power/ground when the engine/ignition commanded. Replace sensor if heater is open or out of spec.
  6. Test response electrically: with scope or scan tool record the voltage waveform during transient conditions. If waveform is sluggish (slow rise/fall) and wiring/power/ground are good, the sensor is likely defective.
  7. Check for exhaust leaks upstream of sensor and repair if present, then retest.
  8. Repair wiring or connector faults found. If wiring and engine systems are good and sensor is old or contaminated, replace the Bank 1 Sensor 1 with OE-equivalent sensor.
  9. After repairs clear codes and confirm proper operation over driving cycles and that the code does not return.

Likely causes

  • Worn/contaminated sensor (most common with age/high mileage)
  • Damaged or corroded connector or wiring (intermittent/slow signal)
  • Exhaust leak between cylinder head and sensor
  • Long-term fuel trim or injection problem creating poor sensor switching

Fault status

⚠️ Status
Bank 1 Sensor 1 O2 sensor response is slower than expected; possible slow-switching sensor, wiring problem, or upstream condition affecting readings.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1.0-2.5 hours
Repair manuals

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Code

P0133

LAND ROVER P — Powertrain

slow circuit of the O2 sensor (bank 1 sensor 1)

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

Causes

  • Aging or contaminated upstream O2 sensor (slow to switch)
  • Wiring harness damage, corroded connector, or poor ground to the sensor
  • Exhaust leak upstream of the sensor affecting readings
  • Fuel system or ignition issues causing unstable/abnormal switching (rich/lean events, misfire)
  • Faulty sensor heater (sensor not reaching operating temperature quickly)
  • Excessive exhaust backpressure or catalytic converter problem affecting sensor readings

Symptoms

  • Check Engine Light (MIL) illuminated
  • Poor fuel economy
  • Rough idle or hesitation during acceleration
  • Higher than normal emissions (failed inspection)
  • Delayed O2 voltage switching on live data during snap-throttle tests

What to check

  • Read and record freeze frame and pending codes; verify P0133 is current and reproducible
  • Scan live O2 sensor voltage (Bank 1 Sensor 1) at operating temp; observe switching behavior during steady state and snap-throttle
  • Check short-term and long-term fuel trims for abnormal values
  • Visually inspect sensor, connector, and wiring for damage, corrosion, heat damage, or oil/coolant contamination
  • Check for exhaust leaks upstream of the sensor (listen, use smoke or soapy water if safe)
  • Measure heater circuit resistance and supply voltage (if sensor has heater) with connector disconnected — compare to spec

Signal parameters

  • Typical narrowband upstream O2 voltage range: ~0.1 V (lean) to ~0.9 V (rich)
  • Healthy sensor should switch rapidly (several times per second) between lean and rich under steady operating conditions; response time typically measured in tens to low hundreds of milliseconds (manufacturer-specific)
  • Slow-response symptom: delayed voltage transition when air/fuel is changed or after snap throttle
  • Heater circuit: expected supply ≈ battery voltage when commanded; heater resistance is usually low (consult vehicle spec)

Diagnostic algorithm

  1. Verify the code: clear the code, drive or re-run readiness checks to see if P0133 returns and capture freeze-frame data.
  2. Monitor live data: warm the engine to normal operating temperature and observe Bank 1 Sensor 1 voltage. Perform snap-throttle or induced lean/rich events (introduce vacuum leak briefly or tap throttle) to see if the sensor switches quickly. Compare with Bank 2 Sensor 1 if present.
  3. Check fuel trims: if long-term short-term fuel trims are extreme, diagnose underlying fuel/ignition issues (fuel pressure, injectors, misfire, vacuum leaks) before replacing the sensor.
  4. Inspect wiring/connectors: unplug connector, inspect pins for corrosion, bent pins, or water ingress. Backprobe and check for proper reference voltage and ground while monitoring sensor signal.
  5. Test heater circuit: with connector disconnected measure heater resistance and verify power/ground when the engine/ignition commanded. Replace sensor if heater is open or out of spec.
  6. Test response electrically: with scope or scan tool record the voltage waveform during transient conditions. If waveform is sluggish (slow rise/fall) and wiring/power/ground are good, the sensor is likely defective.
  7. Check for exhaust leaks upstream of sensor and repair if present, then retest.
  8. Repair wiring or connector faults found. If wiring and engine systems are good and sensor is old or contaminated, replace the Bank 1 Sensor 1 with OE-equivalent sensor.
  9. After repairs clear codes and confirm proper operation over driving cycles and that the code does not return.

Likely causes

  • Worn/contaminated sensor (most common with age/high mileage)
  • Damaged or corroded connector or wiring (intermittent/slow signal)
  • Exhaust leak between cylinder head and sensor
  • Long-term fuel trim or injection problem creating poor sensor switching

Fault status

⚠️ Status
Bank 1 Sensor 1 O2 sensor response is slower than expected; possible slow-switching sensor, wiring problem, or upstream condition affecting readings.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1.0-2.5 hours
320

Browse 320 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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+100 karma for a short comment :)
Keep it short and practical. Up to 500 characters.
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Code

P0133

MITSUBISHI P — Powertrain

Oxygen sensor(front) response

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

Causes

  • Aging or contaminated upstream O2 sensor (slow to switch)
  • Wiring harness damage, corroded connector, or poor ground to the sensor
  • Exhaust leak upstream of the sensor affecting readings
  • Fuel system or ignition issues causing unstable/abnormal switching (rich/lean events, misfire)
  • Faulty sensor heater (sensor not reaching operating temperature quickly)
  • Excessive exhaust backpressure or catalytic converter problem affecting sensor readings

Symptoms

  • Check Engine Light (MIL) illuminated
  • Poor fuel economy
  • Rough idle or hesitation during acceleration
  • Higher than normal emissions (failed inspection)
  • Delayed O2 voltage switching on live data during snap-throttle tests

What to check

  • Read and record freeze frame and pending codes; verify P0133 is current and reproducible
  • Scan live O2 sensor voltage (Bank 1 Sensor 1) at operating temp; observe switching behavior during steady state and snap-throttle
  • Check short-term and long-term fuel trims for abnormal values
  • Visually inspect sensor, connector, and wiring for damage, corrosion, heat damage, or oil/coolant contamination
  • Check for exhaust leaks upstream of the sensor (listen, use smoke or soapy water if safe)
  • Measure heater circuit resistance and supply voltage (if sensor has heater) with connector disconnected — compare to spec

Signal parameters

  • Typical narrowband upstream O2 voltage range: ~0.1 V (lean) to ~0.9 V (rich)
  • Healthy sensor should switch rapidly (several times per second) between lean and rich under steady operating conditions; response time typically measured in tens to low hundreds of milliseconds (manufacturer-specific)
  • Slow-response symptom: delayed voltage transition when air/fuel is changed or after snap throttle
  • Heater circuit: expected supply ≈ battery voltage when commanded; heater resistance is usually low (consult vehicle spec)

Diagnostic algorithm

  1. Verify the code: clear the code, drive or re-run readiness checks to see if P0133 returns and capture freeze-frame data.
  2. Monitor live data: warm the engine to normal operating temperature and observe Bank 1 Sensor 1 voltage. Perform snap-throttle or induced lean/rich events (introduce vacuum leak briefly or tap throttle) to see if the sensor switches quickly. Compare with Bank 2 Sensor 1 if present.
  3. Check fuel trims: if long-term short-term fuel trims are extreme, diagnose underlying fuel/ignition issues (fuel pressure, injectors, misfire, vacuum leaks) before replacing the sensor.
  4. Inspect wiring/connectors: unplug connector, inspect pins for corrosion, bent pins, or water ingress. Backprobe and check for proper reference voltage and ground while monitoring sensor signal.
  5. Test heater circuit: with connector disconnected measure heater resistance and verify power/ground when the engine/ignition commanded. Replace sensor if heater is open or out of spec.
  6. Test response electrically: with scope or scan tool record the voltage waveform during transient conditions. If waveform is sluggish (slow rise/fall) and wiring/power/ground are good, the sensor is likely defective.
  7. Check for exhaust leaks upstream of sensor and repair if present, then retest.
  8. Repair wiring or connector faults found. If wiring and engine systems are good and sensor is old or contaminated, replace the Bank 1 Sensor 1 with OE-equivalent sensor.
  9. After repairs clear codes and confirm proper operation over driving cycles and that the code does not return.

Likely causes

  • Worn/contaminated sensor (most common with age/high mileage)
  • Damaged or corroded connector or wiring (intermittent/slow signal)
  • Exhaust leak between cylinder head and sensor
  • Long-term fuel trim or injection problem creating poor sensor switching

Fault status

⚠️ Status
Bank 1 Sensor 1 O2 sensor response is slower than expected; possible slow-switching sensor, wiring problem, or upstream condition affecting readings.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1.0-2.5 hours
406

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

MITSUBISHI

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