Secondary Air Injection Solenoid Valve - N112-, CHECKING

General Description 

The secondary air injection system injects air into the exhaust on a cold-start of the engine for about 45 - 100 s. and serves to quickly heat the catalytic converter(s) for improved emissions. A "pressure based secondary air diagnostics" function is used. In this system, the Engine Control Module -J623- controls the Secondary Air Injection Solenoid Valve -N112-, which allows the air quantity necessary to be injected into the exhaust.

Special tools and workshop equipment required 

• Multimeter.
• Wiring Diagram.
• Scan Tool.

Test requirements

• Fuses OK.
• Battery voltage OK.
• Switch OFF all electrical and electronic accessories.
• Vehicles with automatic transmission, ensure the selector lever position is in "P".
• Vehicles with manual transmission, ensure the shifter lever position is in "N" with the parking brake applied.
• Observe all safety precautions: SAFETY PRECAUTIONS .
• View clean working conditions: CLEAN WORKING CONDITIONS .

Test Procedure 

Step	Procedure	Result / Action to Take
1	PERFORM: Preliminary Check to verify the customers complaint. Refer to PRELIMINARY CHECK . -- Was Complaint verified?	-- YES: GO TO: Step 2. -- NO: GATHER more information from customer about the complaint.
2	IGNITION: OFF. DISCONNECT: Secondary Air Injection Solenoid Valve -N112- harness connector. CHECK: Secondary Air Injection Solenoid Valve -N112- component connector terminals 1 to 5 for resistance. SPECIFIED VALUE: 5 - 35 Ω (@ approx. 20° C). -- Was Value obtained?	-- YES: GO TO: Step 3. -- NO: REPLACE: Secondary Air Injection Solenoid Valve -N112-. Refer to appropriate repair information. GO TO: Step 5.
3	IGNITION: ON. CHECK: Secondary Air Injection Solenoid Valve -N112- harness connector terminal 5 to ground for voltage. SPECIFIED VALUE: Battery voltage. IGNITION: OFF. -- Was Value obtained?	-- YES: GO TO: Step 4. -- NO: PERFORM: Visual Inspection of wiring and component. CHECK: Wiring for open, high resistance, short or harness connector for damage, corrosion, loose or broken terminals. REPAIR: Faulty wiring or connector. GO TO: Step 5.
4	REMOVE: Engine Control Module - J623-. Refer to appropriate repair information. CHECK: Secondary Air Injection Solenoid Valve -N112- harness connector terminal 1 to the Engine Control Module - J623- harness connector T105 / 21 for resistance. SPECIFIED VALUE: 0.5 Ω (± 0.3 Ω). -- Was Value obtained?	-- YES: TIP: The Secondary Air Injection Solenoid Valve -N112- may fail under loaded operation; please swap a known good Secondary Air Injection Solenoid Valve -N112- prior to continuing to the next step. GO TO: Step 5. -- NO: PERFORM: Visual Inspection of wiring and component. CHECK: Wiring for open, high resistance, short or harness connector for damage, corrosion, loose or broken terminals. REPAIR: Faulty wiring or connector. GO TO: Step 5.
5	Final Procedure  Perform a road test to verify repair. -- Does the original DTC return?	-- YES: CHECK: Engine Control Module -J623- harness connector for any damaged, pushed-out pins. REPAIR: As necessary. If all electrical connections are OK: REPLACE: Engine Control Module -J623-. Refer to appropriate repair information. Clear the DTC's. Refer to DIAGNOSTIC MODE 04 - ERASE DTC MEMORY . Repair is complete. Generate Readiness Code. Refer to READINESS CODE . Return vehicle to Customer. -- NO: Perform the diagnostic procedure for any DTC's. If no DTC's return, the repair is complete. Return vehicle to customer.