Service Information

Orlando

DTC P2245, P2246, or P2251 - LNP or LNQ

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 Descriptors

DTC P2245 00: HO2S Reference Voltage Circuit Low Voltage Sensor 1

DTC P2246 00: HO2S Reference Voltage Circuit High Voltage Sensor 1

DTC P2251 00: HO2S Low Reference Circuit Sensor 1

Diagnostic Fault Information

Circuit	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performance
Heater Voltage Supply	P0030 00	P0030 00	-	-
Reference Voltage (Signal)	P2245 00	P2246 00	P2246 00	P2A00
Heater Low Control	P0031 00	P0030 00	P0032 00	-
Pump Current Control	P2238 00	P2237 00	-	-
Low Reference (Ground)	-	P2251 00	-	-

The wide band heated oxygen sensor (HO2S) measures the amount of oxygen in the exhaust stream more quickly and accurately than the switching style HO2S. The wide band sensor consists of an oxygen sensing cell, an oxygen pumping cell, and a heater. The exhaust gas sample passes through a diffusion gap between the sensing cell and the pumping cell. The engine control module (ECM) supplies a signal voltage to the HO2S and uses this voltage as a reference to the amount of oxygen in the exhaust system. An electronic circuit within the ECM controls the pump current through the oxygen pumping cell in order to maintain a constant signal voltage. The ECM monitors the voltage variation on the signal circuit and attempts to keep the voltage constant by increasing or decreasing the amount of current flow or reversing the direction of the current flow to the pumping cell. By measuring the direction and amount of current required to maintain the signal voltage.

Conditions for Running the DTC

P2245 00 or P2246 00

•	DTCs P0030, P0031, P0032 are not set.

•	The ignition voltage is between 10-18 V.

•	The engine speed is greater than 80 RPM.

•	The HO2S 1 heater is at operating temperature.

•	DTC P2243 runs continuously when the above conditions are met for 2 s.

P2251 00

•	DTCs P0030, P0031, P0032 are not set.

•	The ignition voltage is between 10.7-18.1 V.

•	The engine is running.

•	The estimated exhaust temperature is less than 900°C (1 652°F).

•	The HO2S 1 voltage is between 1.47-1.53 V.

•	The HO2S 1 heater temperature has been within the normal range for more than 20 s.

•	HO2S 1 internal resistance is more than 570 Ω.

•	The following are true for more than 30 s.

-	The HO2S 1 heater is ready.

-	The engine is running.

-	The ignition voltage is more than 11 V.

•	DTC P2251 runs continuously when the above conditions are met for 10 min.

Conditions for Setting the DTC

P2245 00

•	The ECM detects an short to ground on the reference voltage circuit.

•	DTC P2245 00 sets within 4 s when the above condition is met continuously, or within 50 s when the above condition is met cumulatively.

P2246 00

•	The ECM detects an short to voltage on the reference voltage circuit.

•	DTC P2246 00 sets within 4 s when the above condition is met continuously, or within 50 s when the above condition is met cumulatively.

P2251

•	The ECM detects that the reference ground circuit is open.

•	DTC P2251 sets within 4 s when the above condition is met continuously, or within 50 s when the above condition is met cumulatively.

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Component 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

Control Module References for scan tool information

Circuit/System Verification

Clear the DTCs with a scan tool.
Operate the vehicle within the conditions for running and setting the DTC. The DTC should not set.
Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

Circuit/System Testing

Note: You must perform the Circuit/System Verification before proceeding with Circuit/System Testing.

Ignition OFF, disconnect the harness connector at the B52 Heated Oxygen Sensor.
Disconnect the X1 harness connector at the K20 Engine Control Module
Test for less than 5 Ω between both the harness connectors on the terminals as listed below:

•	B52 Heated Oxygen Sensor Terminal A and the K20 Engine Control Module terminal 55

•	B52 Heated Oxygen Sensor Terminal B and the K20 Engine Control Module terminal 54

•	B52 Heated Oxygen Sensor Terminal E and the K20 Engine Control Module terminal 57

•	B52 Heated Oxygen Sensor Terminal F and the K20 Engine Control Module terminal 56

⇒	If greater than the specified range, test the circuit for an open/high resistance

Test for infinite resistance between each B52 Heated Oxygen Sensor circuit terminal and ground.

⇒	If less than the specified value, repair the short to ground as necessary.

Test for infinite resistance between each B52 Heated Oxygen Sensor circuit terminals.

⇒	If less than the specified value, repair as necessary.

Ignition ON, test for less than 0.3 V between each B52 Heated Oxygen Sensor circuit terminal and ground.

⇒	If greater than the specified range, repair the short to voltage as necessary.

If all circuits test normal, replace the B52 Heated Oxygen Sensor and verify the DTC does not reset

⇒	If the DTC resets, replace the K20 Engine Control Module.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

•	Heated Oxygen Sensor Replacement

•	Control Module References for ECM replacement, setup and programming