Diagnostic Method: Notes

Measure secondary air delivery pipe pressure, pulse of secondary air delivery pipe pressure and secondary air pipe airflow amount.

Pump supply pressure diagnosis 

Perform system function diagnosis by comparing the pressure when the secondary air pump is OFF and the pressure increase when it is ON.

Combination valve both closed pulse diagnosis 

Perform open stuck diagnosis of both combination valves using delivery pipe pressure pulse when both combination valves are closed. Determine which side of valves is stuck open by comparing secondary air flow amount when RH combination valve is closed with that when LH combination valve is closed.

Combination valve change over pressure diagnosis 

Perform close stuck diagnosis of right hand combination valve using variation of delivery pipe pressure when the right hand combination valve turns closed → open.

Perform close stuck diagnosis of left hand combination valve using variation of delivery pipe pressure when the left hand combination valve turns open → closed.

Overflow diagnosis 

Perform secondary air system flow abnormality diagnosis using both sides of combination valves secondary air amount when both are closed.

Judgment Value 

Pump supply pressure diagnosis 

Judge as NG if Delivery pipe pressure does not rise though it should when the secondary air pump turns OFF → ON.

Judge as NG when the following conditions are established. Judge as OK and clear the NG when the following conditions are not established.

Malfunction Criteria	Threshold Value	DTC
Secondary air delivery pipe pressure (after barometric pressure compensation)	< 1 kPa (7 mmHg, 0.3 inHg)	P0410

Combination valve both closed pulse diagnosis 

Calculate voltage pulse of the pump supply pipe pressure when both combination valves are closed. The calculation should be small because there is no pulse from supply pipe pressure with both combination valves closed. When the calculation is large, determine that either of the combination valves is stuck open. Determine which side of valves is stuck open by comparing secondary air flow amount when the RH combination valve is closed with that when the LH combination valve is closed. Air flow amount is larger on the open stuck valve.

Judge as NG when the following conditions are established. Judge as OK and clear the NG when the following conditions are not established.

Malfunction Criteria	Threshold Value	DTC
Pulse calculation value when both combination valves are closed	> Value from Map 3	P2440
Air flow amount when the right bank is closed (value from Map 4)	≥ Air flow amount when the left bank is closed (value from Map 5)
Pulse calculation value when both combination valves are closed	> Value from Map 3	P2442
Air flow amount when the left bank is closed (value from Map 5)	> Air flow amount when the right bank is closed (value from Map 4)

Combination valve change over pressure diagnosis 

Delivery pipe pressure should vary when the LH combination valve turns open → closed. When the variation is small, determine that the LH combination valve is stuck closed.

Judge as NG when the following conditions are established. Judge as OK and clear the NG when the following conditions are not established.

Malfunction Criteria	Threshold Value	DTC
Pressure variation value when the LH combination valve is switched	< Value from Map 6	P2443

Delivery pipe pressure should vary when the RH combination valve turns closed → open. When the variation is small, determine that the RH combination valve is stuck closed.

Judge as NG when the following conditions are established. Judge as OK and clear the NG when the following conditions are not established.

Malfunction Criteria	Threshold Value	DTC
Pressure variation value when the RH combination valve is switched	< Value from Map 7	P2441

Overflow diagnosis 

Judge as secondary air system flow abnormality either if there is excessive secondary air flow amount with the RH combination valve closed, or if there is excessive secondary airflow amount with the LH combination valve closed.

Malfunction Criteria	Threshold Value	DTC
Air flow amount when the right bank is closed (value from Map 4)	> Value from Map 8	P0411
or
Air flow amount when the left bank is closed (value from Map 5)	> Value from Map 9
Voltage at PORL measurement - Voltage at POR measurement	≤ 4 V
Voltage at PORL measurement - Voltage at POL measurement	≤ 4 V

PORL: Both banks all closed pressure

PORL: Both banks all closed pressure

POL: Left bank all closed pressure