P2441
DTC P2441 SECONDARY AIR INJECTION SYSTEM SWITCHING VALVE STUCK CLOSE BANK 1CIRCUIT DESCRIPTION
DTC Detection Conditions:
The Secondary Air injection (AI) system consists of an air pump, the Air Switching Valve (ASV), a pressure sensor, the Air Injection Control Driver (AID) and the ECM. For a short time after cold engine starts, the AI system pumps secondary air to the exhaust port of the cylinder head to purify the exhaust emissions. The secondary air is supplied by the air pump and is pumped to the exhaust port through the ASV.
The AID drives the ASV and the air pump according to command signals transmitted by the ECM. The pressure sensor detects the pressure in the secondary air passage when the AI system is ON and OFF, and transmits pressure signal to the ECM.
The AID is not only equipped to drive the pump and valve, but also with a diagnosis function to detect malfunctions in the AI system circuit.
HINT: As a large current is required to drive the air pump and ASV, an AID has been added to the previous system.
HINT:
Air switching valve normal operation:
When the Air Switching Valve (ASV) is open, exhaust gas pulsation occurs in the secondary air passage.
When the ASV is closed, exhaust gas pulsation does not occur in the secondary air passage.
MONITOR DESCRIPTION
Monitor Strategy:
Typical Enabling Conditions:
Typical Malfunction Thresholds:
Monitor Result:
The ECM monitors the pressure in the secondary air passage using the pressure sensor connected to the ASV of the Secondary Air Injection (AI) system.
If either of the following conditions occurs, the ECM interprets it as a malfunction of the secondary AI system, and illuminates the MIL and sets a DTC:
- Exhaust gas pulsation is detected by the pressure sensor despite the ECM commanding the ASV to close.
- Exhaust gas pulsation is not detected by the pressure sensor despite the ECM commanding the ASV to open.
Wiring Diagram:
Wiring Diagram:
Step 1:
Step 2:
Step 2 (contd.):
Step 3 - 4:
Step 5:
Step 6 - 7:
Step 8 - 10:
Step 11:
INSPECTION PROCEDURE
HINT:
Determination by ECM monitoring:
The ECM locates malfunctions in the Secondary Air Injection (AI) system by detecting the pressure in the AI passage between the air pump and Air Switching Valve (ASV) and sets a DTC. Soon after cold engine starts, the monitor runs for a short time while the AI system is both ON and OFF. The ECM detects both the pressure and the exhaust pulsation and compares them.
The 4 patterns are AI system pressure conditions in the AI system passage.
If the detected pressure is high, the air pump is assumed to be ON and if it alternates sharply*, the ASV is assumed to be open. The ECM locates malfunctions from the combination of pressures detected when the AI system is ON and OFF.
*: The exhaust pulsation value is calculated in the ECM. If the calculated value exceeds a certain level, the ECM determines that the exhaust pulsation is in the AI system.
HINT:
- In case 3, as the pressure sensor detects a slight pump operation pulsation, the detected value is not constant. Since the pump outlet is blocked by closing the ASV, the average pressure is higher than in case 1 (approximately 20 to 30 kPa).
- In case 1, the average pressure is approximately 9 to 11 kPa. The value of 2.5 kPa indicated in the table is a threshold for detecting pump malfunctions.
HINT:
- If the vacuum hose between the ASV and the pressure sensor is not connected correctly, case 4 may occur.
- By using a hand-held tester to perform the AIR INJ CHECK operation in the SYSTEM CHECK, air-fuel ratio and the pressure in the secondary air injection system passage can be checked while the secondary air injection system is operating. This helps technicians to troubleshoot the system when it malfunctions. Furthermore, PENDING CODES also can be checked by performing SYSTEM CHECK / AUTOMATIC OPERATION after the repair.
- Read freeze frame data using a hand-held tester. Freeze frame data record the engine condition when malfunctions are detected. When troubleshooting, freeze frame data can help determine if the vehicle was moving or stationary, if the engine was warmed up or not, if the air-fuel ratio was lean or rich, and other data, from the time the malfunction occurred.
SYSTEM CHECK:
The pressure in the secondary air passage can be checked using a hand-held tester.
a. Start the engine and warm it up.
b. Turn the ignition switch to OFF.
c. Connect a hand-held tester to the DLC3.
d. Turn the ignition switch to ON and turn the tester ON.
e. Select the following menu items:
DIAGNOSIS / ENHANCED OBD II / SYSTEM CHECK / AIR INJ CHECK / MANUAL OPERATION / AP: ON, ASV: OPEN and AP: OFF, ASV CLOSE.
HINT: When MANUAL OPERATION is selected, the tester initialization (atmospheric pressure measurement) is performed automatically. The initialization takes 10 seconds. After the initialization, AP and ASV operation can be selected.
f. Start the engine.
g. Perform the AI system intrusive operation while the engine is idling.
h. Check that the air pump (AIR PUMP), ASV and pressure in the AI system passage (PRESSURE) displayed on the tester, indicate the conditions shown in the table.
i. Turn the ignition switch to OFF.
NOTE:
- This AIR INJECTION CHECK only allows technicians to operate the AI system for a maximum of 5 seconds. Furthermore, the check can only be performed up to 4 times per trip. If the test is repeated, intervals of at least 30 seconds are required between checks. While AI system operation using the hand-held tester is prohibited, the tester display indicates the prohibition (WAIT or ERROR).
If an ERROR as shown in the illustration on the left is displayed on the tester during the test, stop the engine for 10 minutes, and then try again.
- Performing the AIR INJ CHECK repetitively may cause damage to the AI system. If necessary, leave an interval of several minutes between SYSTEM CHECK operations to prevent the system from overheating.
- When performing the AIR INJ CHECK operation after the battery cable has been reconnected, wait for 7 minutes with the ignition switch turned to ON or the engine running.
- Turn the ignition switch to OFF when the AIR INJ CHECK operation finishes.
CHECK FOR INTERMITTENT PROBLEMS
HINT:
Hand-held tester only:
Inspect the vehicle's ECM using check mode. Intermittent problems are easier to detect with a hand-held tester when the ECM is in check mode. In check mode, the ECM uses 1trip detection logic, which is more sensitive to malfunctions than normal mode (default), which uses 2trip detection logic.
a. Clear DTCs.
b. Switch the ECM from normal mode to check mode using a hand-held tester.
c. Perform a simulation test.
d. Check and wiggle the harness(es), connector(s) and terminal(s).