P1154
CIRCUIT DESCRIPTIONThe Heated Oxygen Sensor (HO2S) is a sensor designed to create a voltage relative to the oxygen content in the engine exhaust stream. The control module supplies the HO2S with signal high and low circuits. Ignition voltage and ground are supplied to the HO2S heater by independent circuits. The oxygen content of the exhaust indicates when the engine is operating lean or rich. When the HO2S detects that the engine is operating rich, the signal voltage is high, and decreases the signal voltage as the engine runs leaner. This oscillation above and below the bias voltage, sometimes referred to as activity or switching, can be monitored with the HO2S signal voltage.
The HO2S contains a heater that is necessary in order to quickly warm the sensor to operating temperature. The heater also maintains the operating temperature during extended idle conditions. The HO2S needs to be at a high temperature in order to produce a voltage. When the HO2S reaches operating temperature, the control module monitors the HO2S bias, or reference, voltage. The control module also monitors the HO2S signal voltage for Closed Loop fuel control. During normal Closed Loop fuel control operation, the control module will add fuel, or enrich the mixture, when the HO2S detects a lean exhaust content. The control module will subtract fuel, or "lean-out" the mixture, when the HO2S detects a rich exhaust condition.
Certain vehicle models utilize an oxygen sensor behind the catalytic converter in order to monitor catalyst efficiency.
This Diagnostic Trouble Code (DTC) determines if the HO2S is functioning properly. The DTC checks for an adequate number of HO2S voltage transitions above and below the bias range of 30-600 mV. This DTC sets when the Powertrain Control Module (PCM) fails to detect a minimum number of voltage transitions above and below the bias range during the test period.
CONDITIONS FOR RUNNING THE DTC
^ DTCs P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0117, P0118, P0125, P0128, P0200, P0300, P0351-P0358, P0401, P0404, P0405, P0410, P0418, P0443, P0446, P0449, P1120, P1220, P1221, P1258, or P1404 are not set.
^ The Secondary Air Injection (AIR) and the Exhaust Gas Recirculation (EGR) diagnostics are not active.
^ The system voltage is above 9 volts.
^ The system is in a Closed Loop.
^ The Engine Control Temperature (ECT) is more than 57°C (135°F).
^ The engine has been running for more than 160 seconds.
^ The Mass Air Flow (MAF) is between 15-55 g/s.
^ The engine speed is between 1,100-3,000 RPM.
^ The EVAP canister purge is active.
^ The Accelerator Pedal Position (APP) indicated angle is above 5 percent.
CONDITIONS FOR SETTING THE DTC
The PCM determines that the HO2S transition time ratio is not at the expected value.
ACTION TAKEN WHEN THE DTC SETS
^ The control module illuminates the Malfunction Indicator Lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
^ The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.
CONDITIONS FOR CLEARING THE MIL/DTC
^ The control module turns OFF the Malfunction Indicator Lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
^ A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
^ A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
^ Use a scan tool in order to clear the MIL and the DTC.
DIAGNOSTIC AIDS
^ Using the Freeze Frame/Failure Records data may aid in locating an intermittent condition. If the DTC cannot be duplicated, the information included in the Freeze Frame/Failure Records data can be useful in determining how many miles since the DTC set. The Fail Counter and Pass Counter can also be used to determine how many ignition cycles the diagnostic reported a pass or a fail. Operate vehicle within the same Freeze Frame conditions, such as RPM, load, vehicle speed, temperature etc., that you observed. This will isolate when the DTC failed.
^ An oxygen supply inside the HO2S is necessary for proper operation. This supply of oxygen is provided through the HO2S wires. All HO2S wires and connections should be inspected for breaks or contamination. Refer to Heated Oxygen Sensor (HO2S) Wiring Repairs in Diagrams.
For an intermittent, refer to Intermittent Conditions. Intermittent Conditions
TEST DESCRIPTION
Steps 1-4:
Steps 5-9:
Steps 10-19:
The numbers below refer to the step numbers on the diagnostic table.
2. When DTCs P1134 and P1154 are set at the same time, this is a good indication that a fuel contamination condition is present.
4. The use of leaded fuel may be indicated by the removal or tampering of the fuel filler restrictor. An HO2S contaminated by silicone will have a white, powdery deposit on the portion of the HO2S that is exposed to the exhaust stream. The usual cause of the contamination is the use of unapproved silicone RTV engine gasket material or the use of silicone-based sprays or fluids within the engine. If the cause of this contamination is not corrected, the replacement HO2S will also be contaminated.
7. Even small exhaust leaks can cause a slow response from the H02S.
12. An HO2S contaminated by silicone will have a white, powdery deposit on the portion of the HO2S that is exposed to the exhaust stream. The usual cause of the contamination is the use of unapproved silicone RTV engine gasket material or the use of silicone-based sprays or fluids within the engine. If the cause of this contamination is not corrected, the replacement HO2S will also be contaminated.
13. If the voltage observed in step 8 is less than the specified range, a short between the high and low circuits or a short between the high circuit and ground is indicated. With the HO2S and the PCM disconnected, the resistance between the high and low circuits and the resistance between the high circuit and ground should measure infinite. If the voltage observed in step 8 is more than the specified range, a short between the high circuit and a voltage source is indicated.
14. If the voltage observed in step g is not below the specified voltage, a high resistance in the high or low circuit is indicated. Good circuit continuity measures less than 5 ohms with the PGM and sensor disconnected. Measure between the PCM connector and the HO2S connector. Ensure that the PCM terminal contact is good.