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Engine Management – V6 – Diagnostics Page 6C1-2–210
• The internal HO2S signal voltage switches at the same rate as the heater circuit. • The above condition occurs 4 times out of 6 as the heater is turned off. DTC P2251 or P2254 The ECM detects the following conditions: • The internal HO2S signal voltage changes greater than 10 mV as the heater control switches. • The above condition occurs 20 times in the last 10 seconds. Conditions for Clearing the DTC The HO2S signal circuit shorted to heater control circuit DTCs are Type ‘B’ DTCs. Refer to 1.4 Diagnostic Trouble Codes in this Section, for action taken when Type ‘B’ DTC sets and conditions for clearing Type ‘B’ DTCs. Additional Information • Refer to 6C1-1 Engine Management – V6 – General Information for details of the HO2S system operation. • For an intermittent fault condition, refer to 5.2 Intermittent Fault Conditions in this Section. • The HO2S must be tightened correctly. A loose HO2S will trigger these DTCs. • Since fault condition in a wiring connector may trigger DTCs, always test the connectors related to this diagnostic • To assist diagnosis, refer to 3 Wiring Diagrams and Connector Charts in this Section, for the system wiring diagram and connector charts. DTC P2231, P2232, P2234, P2235, P2251or P2254 Diagnostic Table Step Action Yes No 1 Has the Diagnostic System Check been performed? Go to Step 2 Refer to 4.4 Diagnostic this Section 2 1 Switch off the ignition for 30 seconds. 2 Start the engine. 3 Allow the engine to reach the normal operating temperature. 4 Increase the engine speed to 2,000 rpm for 10 seconds. 5 Using Tech 2, select the DTC display function. Does DTC P2231, P2232, P2234, P2235, P2251 or P2254 fail this Go to Step 3 Refer to Additional Information in this DTC 3 1 Disconnect the appropriate HO2S connector. 2 From the HO2S to the sensor wiring connector, test the • Reference signal circuit, • low reference circuit, • pump current, • input pump current.
Refer to 8A Electrical - Body and Chassis for information on Was any fault found? Go to Step 6 Go to Step 4 |