DTC P1166. Chevrolet Vivant 2007

For 1990-2009 cars only

Makes 🢒 Chevrolet 🢒 2007 🢒 Vivant 🢒 Engine 🢒 Engine Controls and Fuel - 2.0L (L34 GMDAT) 🢒 DTC P1166

Diagnostic Instructions

•	Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

•	Review Strategy Based Diagnosis for an overview of the diagnostic approach.

•	Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptor

DTC P1166: HO2S Circuit Low Voltage During Power Enrichment Sensor 2

Diagnostic Fault Information

Circuit	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performance
HO2S Signal	P0131, P0137, P1137, P1166	P0134, P0140	P0132, P0138, P1138, P2297	P0133
Low Reference	--	P0134, P0140	P0132, P0138, P1138, P2297	P0133

Typical Scan Tool Data

HO2S 1 and 2

Circuit	Short to Ground	Open	Short to Voltage
Operating Conditions: Engine operating in Closed Loop. Parameter Normal Range: Fluctuates above and below 350-500 mV.
HO2S 1 and 2 Signal	0 mV	400-415 mV	1000 mV
Low Reference	--	400-415 mV	1000 mV

Circuit

Short to Ground

Open

Short to Voltage

Operating Conditions: Engine operating in Closed Loop.

Parameter Normal Range: Fluctuates above and below 350-500 mV.

HO2S 1 and 2 Signal

0 mV

400-415 mV

1000 mV

Low Reference

400-415 mV

1000 mV

The heated oxygen sensors (HO2S) are used for fuel control and catalyst monitoring. Each HO2S compares the oxygen content of the surrounding air with the oxygen content of the exhaust stream. When the engine is started, the control module operates in an Open Loop mode, ignoring the HO2S signal voltage while calculating the air-to-fuel ratio. The control module supplies the HO2S with a reference, or bias voltage of about 450 mV. While the engine runs, the HO2S heats up and begins to generate a voltage within a range of 0-1,000 mV. This voltage will fluctuate above and below the bias voltage. Once sufficient HO2S voltage fluctuation is observed by the control module, Closed Loop is entered. The control module uses the HO2S voltage to determine the air-to-fuel ratio. An HO2S voltage that increases above bias voltage toward 1,000 mV indicates a rich fuel mixture. An HO2S voltage that decreases below bias voltage toward 0 mV indicates a lean fuel mixture.

The heating elements inside each HO2S heat the sensor to bring the sensor up to operating conditions faster. This allows the system to enter Closed Loop earlier and the control module to calculate the air-to-fuel ratio sooner.

The HO2S utilizes the following circuits:

•	A signal circuit

•	A low reference circuit

•	An ignition 1 voltage circuit

•	A heater control circuit

Conditions for Running the DTC

•	DTCs P0106, P0107, P0108, P0117, P0118, P0122, P0123, P0171, P0172, P0201, P0202, P0203, P0204, P0300, P0336, P0337, P0351, P0352, P0402, P0404, P0405, P0406, P0443, P0502, P0506, P0507, and P1404 are not set.

•	The engine airflow is greater than 13.5 g/s.

•	The startup engine coolant temperature is greater than 60°C (140°F).

•	The ignition 1 voltage is greater than 10 volts.

•	The engine has been operating for 60 seconds.

•	The engine is in power enrichment (PE) mode.

•	The DTCs run continuously when the above conditions are met for 3 seconds.

Schematic Reference

Engine Controls Schematics

Connector End View Reference

•	Engine Control Module Connector End Views

•	Engine Controls Connector End Views

Electrical Information Reference

•	Circuit Testing

•	Connector Repairs

•	Testing for Intermittent Conditions and Poor Connections

•	Wiring Repairs

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

•	Scan Tool Data List

•	Scan Tool Data Definitions

•	Scan Tool Output Controls

Circuit/System Verification

With the engine running, observe the heated oxygen sensor 2 (HO2S) voltage parameter. Verify the HO2S sensor 2 parameter is between 350-550 mV.

Circuit/System Testing

Ignition OFF, disconnect the harness connector of the heated oxygen sensor 2 (HO2S).
Ignition ON, verify that the HO2S 2 parameter is between 350-500 mV.

⇒	If less than 350 mV, test the signal circuit of the HO2S sensor 2 for a short to ground. If the circuit/connections test normal, replace the engine control module (ECM).

Verify that none of the following conditions exist:

•	Lean fuel injectors--Refer to Fuel Injector Balance Test with Special Tool .

•	Water intrusion in the HO2S harness connector.

•	Low fuel system pressure--Refer to Fuel System Diagnosis .

•	Fuel that is contaminated--Refer to Alcohol/Contaminants-in-Fuel Diagnosis .

•	Exhaust leaks near the HO2S.

•	Contaminated HO2S--Silicon.

•	Engine vacuum leaks.

⇒	If you find any of the above conditions, repair as necessary.

If all circuits/connections test normal, replace the HO2S sensor 2.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for engine control module replacement, setup, and programming.