925061 Volvo.Penta O-ring

System Operation Description:Use this procedure to troubleshoot the electrical system if a problem is suspected with the oxygen sensors. Also, use this procedure if one of the diagnostic codes in Table 1 is active or easily repeated.
Table 1
Diagnostic Codes Table
J1939 Code and Description Conditions which Generate this Code System Response
3217-3 Aftertreatment Intake %O2 : Voltage Above Normal The Electronic Control Module (ECM) may have detected a short circuit to the +Battery. The ECM may have detected an open circuit in the signal circuit for the oxygen sensor at the turbocharger exhaust outlet. The code is logged.
The amber warning lamp is illuminated.
The ECM uses the last good value from the oxygen sensor for the control of exhaust emissions.
3227-3 Aftertreatment Outlet %O2 : Voltage Above Normal The ECM may have detected a short circuit to the +Battery. The ECM may have detected an open circuit in the signal circuit for the oxygen sensor at the outlet of the catalytic converter.
Illustration 1 g02036913
Oxygen sensor and buffer
(1) Oxygen sensor
(2) Sensor bufferThe oxygen sensors are used to monitor the emission level of the engine exhaust. The ECM utilizes the signal from the oxygen sensors to adjust the air/fuel ratio. This strategy ensures that the engine burns the fuel efficiently. Two oxygen sensors are used for this application. One of the oxygen sensors is mounted in the turbocharger exhaust outlet. The other oxygen sensor is mounted in the output flange of the catalytic converter. Each sensor circuit consists of an oxygen sensor and a sensor buffer. A voltage converter is used to power both sensor circuits.The oxygen sensors are used to detect the level of oxygen in the engine exhaust. The sensors generate voltage signals that are directly proportional to the concentration of oxygen. The usable range of each signal is 150 mV to 750 mV. A lean concentration level will produce a 150 mV signal and a rich concentration level will produce a 750 mV signal. This analog signal is sent to the sensor buffer. Each oxygen sensor utilizes a heating element to heat the sensing element of the sensor. The use of the heating element improves the warmup time and the accuracy of the sensor.Note: The sensors have an operating range of 600° C to 800° C (1100° F to 1500° F). The tip of the sensors may be hot. Use caution when you handle the oxygen sensors.The sensor buffer is used to filter the electronic signal that is sent from the oxygen sensor. The buffer acts as a filter to condition the analog signal before the signal is sent to the ECM.The voltage converter converts a filtered 24 VDC from the ECM to 12 VDC that is used by the sensor circuit. The voltage converter provides 12 VDC to each of the buffers. Each buffer supplies 12 VDC to the oxygen sensor. Each sensor supply is used to power the heating element and the supply circuit for the analog sensor.A -3 diagnostic code indicates that a problem has been detected in the circuit for the sensor signal. The problem may be caused by the wiring, the sensor, the sensor buffer, or the voltage converter.
Illustration 2 g02402537
Schematic of the circuit for the oxygen sensor
Test Step 1. Inspect the Electrical Connectors and the Wiring
Remove the electrical power from the engine.
Illustration 3 g02404356
Location of the components for the oxygen level (right side engine view)
(3) Oxygen sensor for the inlet of the catalytic convertor
(4) Voltage converter
(5) Buffer for the oxygen sensor at the inlet of the catalytic convertor
(6) Buffer for the oxygen sensor at the outlet of the catalytic converter
Illustration 4 g02404397
Location of the components for the oxygen level (catalytic converter view)
(7) Oxygen sensor at the outlet of the catalytic converter
Illustration 5 g02404516
Locations of the connectors at the ECM control box (top side engine view)
(8) J2/P2 ECM connectors
(9) J1/P1 ECM connectors
(10) Harness connector for the sensors at the catalytic converter
Thoroughly inspect the connectors for sensors (3) and (7). Also, thoroughly inspect connectors (8), (9), and (10), the connectors for sensor buffers (5) and (6), and the connector for voltage converter (4). Refer to Testing and Adjusting, "Electrical Connectors - Inspect" for details that are related to inspection of the electrical connectors.
Illustration 6 g02404580
Terminal locations at the J1/P1 ECM connectors that are for the oxygen level
(P1-3) Signal return for the oxygen sensors
(P1-17) Signal for the oxygen sensor at the inlet of the catalytic converter
(P1-27) Signal for the oxygen sensor at the outlet of the catalytic converter
(P1-70) Keyswitch
Illustration 7 g02404600
Terminal locations at the J2/P2 ECM connectors that are for the oxygen level
(P2-28) Supply for the voltage converter
Illustration 8 g02404637
Terminal locations at the harness connector for the sensors that are at the catalytic c