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DTC P1420/17828 - Secondary Air Injection Control Electrical Malfunction

NOTE: DTC is set when Electronic Control Module (ECM) activates secondary air injection solenoid but Heated Oxygen Sensor (HO2S) does not detect secondary air injection.
  1. Inspect secondary air injection solenoid valve connector for looseness and/or corrosion. Repair solenoid valve connector as necessary. Erase DTC memory and test drive vehicle. See CLEARING DTCS in this article. Recheck DTC memory and verify DTC does not reset. If DTC resets, go to next step. If solenoid valve connector was not repaired, go to next step.
  2. Turn ignition off. Disconnect ECM connector. Connect Test Box (VAG 1598/18) to ECM wiring harness. Terminal assignments of test box are identical to ECM connector's.
  3. Using DVOM, check resistance between solenoid valve connector terminal No. 1 and test box socket No. 50. Resistance should be less than 1.5 ohms. If resistance is as specified, go to step 5). If resistance is not as specified, locate and repair open circuit between solenoid valve connector and ECM. Erase DTC memory and test drive vehicle. See CLEARING DTCS in this article. Recheck DTC memory and verify DTC does not reset. If DTC resets, go to next step.
  4. Turn ignition on. Jumper test box sockets No. 1 and 6. Jumper test box socket No. 50 to ground. Check voltage between solenoid valve connector terminals No. 1 and 2. Voltage should be at least 11.5 volts. If voltage is as specified, go to next step. If voltage is not as specified, locate and repair open circuit between solenoid valve connector terminal No. 2 and fuse No. 18 connector lower terminal. Erase DTC memory and test drive vehicle. See CLEARING DTCS in this article. Recheck DTC memory and verify DTC does not reset. If DTC resets, go to step 6).
  5. Check resistance between solenoid valve terminals No. 1 and 2. Resistance should be 40-80 ohms. If resistance is as specified, go to next step. If resistance is not as specified, replace solenoid valve. Erase DTC memory and test drive vehicle. See CLEARING DTCS in this article. Recheck DTC memory and verify DTC does not reset. If DTC resets, go to next step.
  6. Replace faulty ECM. Test drive vehicle. Recheck DTC memory and verify DTC does not reset. If DTC resets, repeat testing procedure.
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