P22C0

Code

Generic P — Powertrain

O2 Sensor Negative Current Control Circuit Low Bank 2 Sensor 2

Brand: Generic

Type: P — Powertrain

Views: UK: 25 EN: 35 RU: 27

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Page language: EN

Causes

Faulty Bank 2 Sensor 2 (downstream O2/UEGO sensor)
Open, shorted, or corroded wiring or connector (signal or sensor ground)
Poor or missing sensor ground or reference
Faulty sensor heater affecting sensor operation
Exhaust leak near the sensor or damaged sensor element
Faulty ECU/PCM or internal driver circuitry

Symptoms

Check Engine Light (MIL) illuminated
Possible failed emissions test
Reduced catalytic converter monitoring or readiness (monitor incomplete)
Possible slight changes in fuel economy or drivability (usually subtle)
Stored freeze-frame and related O2 sensor or catalyst codes

What to check

Read all DTCs and freeze-frame data with a scan tool; note fuel trims and related codes
Confirm sensor type (narrowband vs wideband/UEGO) for proper test method
Visual inspection of sensor, connector, and wiring for damage, corrosion, or exhaust leaks
Backprobe connector with key on/engine running to verify reference voltage/grounds
Check heater circuit resistance and heater supply voltage
Wiggle test wiring while monitoring live data to reproduce the fault

Signal parameters

Downstream narrowband O2: typical voltage 0.1–0.9 V (stable, not used for closed-loop fuel control)
Wideband/UEGO sensors: ECU may command positive and negative pump currents; negative command typically in a small mA range (varies by manufacturer)
Heater supply: ~12 V when active; heater resistance typically a few ohms to a few tens of ohms depending on sensor
Expected steady downstream behavior: minimal rapid swings compared with upstream sensor; catalyst efficiency values should be within monitor thresholds

Diagnostic algorithm

Verify the code and note freeze-frame/fuel trim data. Clear codes and see if code returns.
Identify whether Bank 2 Sensor 2 is a narrowband or wideband sensor to select correct test procedures.
Perform a visual inspection of the sensor, harness, and connector for heat damage, contamination, corrosion, or pin damage. Repair any obvious issues.
With connector disconnected, measure heater resistance and compare to specification. Check heater supply voltage and ground with key on/engine running as required. Repair heater circuit faults.
Backprobe the sensor signal/return and ECU control lines while running. Check for correct reference voltage and solid ground. Look for short to ground or short to voltage.
If wideband, measure commanded pump current and measured pump current (or use manufacturer test values). Verify ECU can command and read negative currents; look for stuck/low current.
Perform a wiggle test on harness while monitoring live data to identify intermittent opens/shorts.
Inspect for exhaust leaks upstream of the sensor and repair if present (can affect readings).
If wiring and connectors check good, swap with an identical known-good sensor (or replace sensor) and retest.
If fault follows wiring repair or sensor replacement, suspect ECU driver fault and consult manufacturer procedures before replacing ECU.

Likely causes

Damaged/corroded connector or wiring to Bank 2 Sensor 2
Failed downstream O2 (wideband/UEGO) sensor
Poor sensor ground or shared ground fault
Heater circuit intermittent (sensor not at correct operating temp)

Fault status

⚠️ Status

O2 sensor negative current control circuit is below expected range for Bank 2 Sensor 2 — possible sensor, wiring/ground, heater, or ECU control circuit fault.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-2.5 hours