P2A03
P2A03Component Location:
General Description
The rear heated oxygen sensor is mounted on the rear side of the Catalytic Converter (warm-up catalytic converter) or in the rear exhaust pipe, which is able to detect catalyst efficiency. The rear heated oxygen sensor (HO2S) produces a voltage between 0 V and 1 V. This rear heated oxygen sensor is used to estimate the oxygen storage capability. If a catalyst has good conversion properties, the oxygen fluctuations are smoothed by the oxygen storage capacity of the catalyst. If the conversion provided by the catalyst is low due to aging, poisoning or misfiring, then the oxygen fluctuations are similar to signals from the front oxygen sensor.
DTC Description
Checking output signals from B2S1 every 12 sec. under detecting condition, if an output signal is near 3.5 V for more than 10 sec., PCM sets P2A03. MIL (Malfunction Indication Lamp) turns on.
DTC Detecting Condition:
Specification:
Schematic Diagram (Part 1):
Schematic Diagram (Part 2):
Signal Waveform:
Monitor Scantool Data
1. Connect Scantool & "ON"
2. Warm up the engine to normal operating temperature.
3. Monitor HO2S voltage (B2/S1) parameter on scantool
Specification: Voltage will vary from 0.1 to 0.9 V
4. Is the HO2S parameter displayed within specifications?
YES - Fault is intermittent caused by poor contact in the sensor's and/or PCM's connector or was repaired and PCM memory was not cleared. Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage. Repair or replace as necessary and go to "Verification of Vehicle Repair" procedure.
NO - Go to "Component Inspection" procedure
Component Inspection
1. Visual Inspection of HO2S
1. Visually/physically inspect following items:
- Inspect the front HO2S for Contaminated, deteriorated or aged Front HO2S
- If contamination is evident on the HO2S, replace contaminated sensor
2. Is the HO2S visually / physically O.K?
YES - Go to "Check Performance of HO2S" as below
NO - Substitute with a known - good HO2S and check for proper operation. If the problem is corrected, replace HO2S and go to "Verification of Vehicle Repair"
2. Check performance of HO2S
1. Connect scantool & Engine "ON"
2. Warm-up the engine to normal engine temperature.
3. Monitor signal waveform of HO2S with scantool
Specification: Voltage will vary from 0.1 to 0.9 V
4. Is the sensor signal switching properly?
YES - Substitute with a known - good PCM and check for proper operation. If the problem is corrected, replace PCM and go to "Verification of Vehicle Repair" procedure.
NO - Substitute with a known - good HO2S and check for proper operation. If the problem is corrected, replace HO2S and go to "Verification of Vehicle Repair" procedure.
CAUTION: There is a memory reset function on scantool that can erase optional parts automatically detected and memorized by PCM. Before or after testing PCM on the vehicle, use this function to reuse the PCM on the others
Verification of Vehicle Repair
After a repair, it is essential to verify that the fault has been corrected.
1. Monitor and record the Freeze Frame Data for the Diagnostic Trouble Code (DTC) which has been diagnosed.
2. Using a Scantool, Clear the DTCs
3. Operate the vehicle within conditions noted in the freeze frame data or enable conditions
4. Monitor that all readiness test have been verified as "Complete"
5. Are any DTCs present?
YES - Go to the applicable troubleshooting procedure.
NO - System is performing to specification at this time.