P2233 - Oxygen Sensor (O2) Signal Circuit Shorted to Heater Circuit (Bank 1 Sensor '3')
System
Powertrain (Engine & Gearbox)
Technical Description
The control module has detected a fault in the Oxygen Sensor (O2) Signal Circuit Shorted to Heater Circuit (Bank 1 Sensor '3') (P2233).
Multimeter Test Points & Nominal Values
| Test Point / Component | Measurement | Nominal Target Range | Test Condition |
|---|---|---|---|
| Oxygen Sensor (O2) Signal Circuit Shorted to Heater Circuit (Bank 1 Sensor '3') – Heater Resistance (Cold) | Resistance (Ω) | 2.5 - 10.0 Ω | Disconnected plug at 20°C |
| Oxygen Sensor (O2) Signal Circuit Shorted to Heater Circuit (Bank 1 Sensor '3') – Signal Voltage | Voltage (V) | 0.10 - 0.90 V, oscillating 1 - 3 Hz | Warm engine closed loop at 2000 RPM |
| Oxygen Sensor (O2) Signal Circuit Shorted to Heater Circuit (Bank 1 Sensor '3') – Pump Current (Wideband) | Current (mA) | -2.0 to +2.0 mA (0 mA at lambda 1.0) | Warm engine, closed loop |
Disconnected plug at 20°C
Warm engine closed loop at 2000 RPM
Warm engine, closed loop
Oscilloscope Waveform Analysis
1 s/div, 200 mV/divPossible Causes
Short to ground on the signal wire or an internal short circuit within Oxygen Sensor (O2) Signal Circuit Shorted to Heater Circuit (Bank 1 Sensor '3')
Bank 1 specific:Inspect wiring harness to cylinder bank 1 (firewall/right bank, exposed to exhaust manifold heat).
Chafed or pinched wiring harness along the signal path to Oxygen Sensor (O2) Signal Circuit Shorted to Heater Circuit (Bank 1 Sensor '3')
Poor ground connection or excessive voltage drop (> 0.1 V) at the ground point for Oxygen Sensor (O2) Signal Circuit Shorted to Heater Circuit (Bank 1 Sensor '3')
Defective internal output driver or reference circuit in the control module for Oxygen Sensor (O2) Signal Circuit Shorted to Heater Circuit (Bank 1 Sensor '3')
Symptoms
4
Recommended Solution
Cross-swap the component on Bank 1 with Bank 2 to rule out mechanical oil passages and internal timing wear.
Check wire insulation resistance to ground (< 1 Ω indicates harness pinched or chafed against engine block/chassis).
Verify loaded supply voltage and harness terminal pins at Oxygen Sensor (O2) Signal Circuit Shorted to Heater Circuit (Bank 1 Sensor '3').
Check circuit continuity and ground-side voltage drop (< 0.05 V) for Oxygen Sensor (O2) Signal Circuit Shorted to Heater Circuit (Bank 1 Sensor '3').
For wideband sensors:monitor pump current (mA) and lambda in scan Live Data during snap-throttle and decel fuel cut.
Mechanic's Tip
O2 sensors measure free oxygen, not fuel. An exhaust leak upstream of the sensor pulls in atmospheric air via venturi pulses, forcing false lean readings and causing the ECM to severely over-fuel.