Code
P1153
TOYOTA
P — Powertrain
Air/Fuel Sensor Circuit Response Bank 1 Sensor 2
Views:
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EN: 35
RU: 19
AI status
Completed
Completed
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Causes
- Failed or aging air/fuel (A/F) sensor (Bank 1, Sensor 2)
- Open, shorted, or high‑resistance wiring or poor connector at the sensor (signal or heater circuit)
- Contaminated sensor (silicone, coolant, oil, leaded fuel, metallic contamination)
- Heater circuit failure (no power, short to ground, or open heater element)
- Exhaust leak upstream of the sensor affecting readings
- Fuel control problems (rich or lean conditions, misfire) causing atypical sensor response
Symptoms
- Malfunction indicator lamp (MIL/CEL) illuminated
- Possible failed emissions test or elevated tailpipe emissions
- No obvious drivability symptoms in many cases (downstream sensor often does not affect feed‑forward fueling)
- Occasional rough idle or poor fuel economy if upstream issues are present
- Stored related diagnostic trouble codes (A/F or O2 sensor and possibly fuel trim or catalyst codes)
What to check
- Read and record all stored codes and freeze frame data; note whether other A/F or O2 codes are present
- Visual inspection of sensor wiring and connector for damage, corrosion, heat damage, or pin push‑outs
- Check for exhaust leaks upstream of the sensor (manifold, gaskets, studs, downpipe)
- Compare live sensor data for Bank 1 Sensor 2 with Bank 2 Sensor 2 and upstream sensor (Bank 1 Sensor 1) using a scan tool
- Measure heater circuit supply voltage and ground at the connector with ignition ON (engine OFF)
- Measure heater resistance (cold) and compare to service manual specification
Signal parameters
- Exact voltage/resistance and timing specs vary by model; consult the vehicle's service manual for values
- Heater circuit: should have battery/ignition‑switched voltage at supply pin and a good ground; heater resistance should match spec (typical sensors often show low ohms)
- Sensor output: downstream A/F sensor should provide a stable, defined signal once at operating temperature and respond quickly to induced changes in exhaust composition
- Response behavior: downstream sensor typically shows slower or different waveform than upstream narrowband but should still switch/shift when exhaust composition is rapidly changed
- If using an oscilloscope, expect a clean, repeatable waveform without excessive noise or dropouts once warm
Diagnostic algorithm
- Confirm DTC P1153 and any related codes. Note freeze frame and mileage.
- Perform visual inspection of the sensor, harness and connector. Repair any obvious damage.
- Check for exhaust leaks upstream of Sensor 2 and repair if found.
- With ignition ON (engine OFF) measure heater supply voltage at the sensor connector; compare to battery/ignition source. If no supply, trace and repair fuse/relay/wiring.
- Measure heater element resistance (cold) and compare to service manual spec. Replace sensor if heater open or out of spec.
- Start engine and allow to reach normal operating temperature. Monitor live data for Bank 1 Sensor 2 and upstream sensor using a scan tool. Look for a valid signal and compare response to Bank 2 Sensor 2.
- Perform a dynamic response test: induce a rich condition (brief propane introduction or shorting injector) or lean condition (vacuum leak) and observe whether Sensor 2 output changes appropriately and promptly. Slow or no change indicates sensor or wiring issue.
- Wiggle test wiring and connector while monitoring signal to find intermittent opens/shorts. Repair/replace damaged wiring or connector.
- If wiring, heater, and exhaust are good but sensor response is poor, replace the Bank 1 Sensor 2 with a correct OEM or equivalent A/F sensor.
- After repairs, clear codes, perform a readiness drive cycle and confirm the DTC does not return and that sensor response is normal.
- If code returns after a known‑good sensor and wiring, consider ECM diagnosis or reflash per manufacturer procedure.
Likely causes
- Sensor has reached end of life or is contaminated and responds slowly
- Damaged wiring harness or corroded connector causing intermittent signal or poor heater supply
- Blown sensor heater or loss of heater supply/ground preventing proper operating temperature
- Exhaust leak allowing outside air to dilute exhaust and confuse the downstream sensor
- Upstream engine issues (fuel pressure, injector, vacuum leak, misfire) creating abnormal exhaust composition
Fault status
Status
Air/Fuel Sensor Circuit Response (Bank 1, Sensor 2) — downstream sensor output/response is not within expected parameters; monitor detected slow or inconsistent response.
Repair difficulty: Medium
Diagnostic time: 1.0-2.5 hours
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