Test Requirements
Ensure all fuses are okay, battery voltage is at least 11.5 volts and fuel pump relay is okay. Ensure all electrical
accessories are off and A/C is off. Ensure engine is mechanically sound. Ensure no exhaust system leaks exist.
Ensure engine coolant temperature is at least 176°F (80°C). On vehicles with M/T, gear shifter must be in
neutral with parking brake set. On vehicles with A/T, selector lever must be in park or neutral with parking
brake set.
Test Procedure
1. Check air induction and secondary air injection system for leaks. If no air leaks are found, go to next step.
If air leaks are found. Repair as necessary. After repairs, erase DTC memory. Verify repair. Test is
complete. Perform ECM relearn procedure. See TEST DRIVE RELEARN PROCEDURE .
2. Connect Scan Tool. See RETRIEVING DIAGNOSTIC TROUBLE CODES . Start engine and idle for
two minutes. Following scan tool manufacturer's instructions, use scan tool to check upstream HO2S
(G39) heater activation. Observe scan tool in upstream HO2S heater activation test mode. Heater
actuation must switch, alternating from on to off. If HO2S heater remains in off mode, go to next step. If
HO2S heater switches, alternating from on to off, go to next step, further testing is needed.
3. Turn ignition off. Raise vehicle and remove HO2 sensors protective cover and disconnect upstream
HO2S (G39) harness connector (Black 6-pin). See Fig. 14 .
4. Using DVOM check resistance of heater circuit on HO2S. Connect DVOM between terminals No. 3 and
4 of HO2S. See Fig. 21 . Resistance should be 2.5-10 ohms at room temperature. If resistance is okay, go
to next step. If resistance is not okay, replace faulty HO2S. After repairs, erase DTC memory. Verify
repair. Test is complete. Perform ECM relearn procedure. See TEST DRIVE RELEARN
PROCEDURE .
5. Start engine and idle. Check voltage supply to HO2S heater. Connect DVOM between terminals No. 3 of
HO2S harness connector and ground. See Fig. 22 . Voltage should be 11.0-14.5 volts. If voltage is okay,
go to next step. If voltage is not okay. Turn ignition off. Using DVOM check resistance of HO2S harness
connector terminal No. 3 to fuel pump relay (J17) harness connector. See ENGINE PERFORMANCE in
SYSTEM WIRING DIAGRAMS article in ELECTRICAL. Resistance should be a maximum of 1.5
ohms. Repair as necessary. After repairs, erase DTC memory. Verify repair. Test is complete. Perform
ECM relearn procedure. See TEST DRIVE RELEARN PROCEDURE .
6. Using DVOM and scan tool, check activation and voltage of heater circuit on HO2S. Connect DVOM
between terminals No. 3 and 4 of HO2S harness connector. See Fig. 22 . Reconnect scan tool. Start
engine and idle. Following scan tool manufacturer's instructions, use scan tool to check HO2S (G39)
heater activation. Observe scan tool in upstream HO2S heater circuit activation mode. Observe voltage on
DVOM. When scan tool shows heater circuit activation On, voltage should be 11.5-14.5 volts. When scan
tool shows heater circuit activation alternating from On to Off, voltage should alternate from 12-0 volts.
Turn ignition off. If voltage and/or activation is not okay, go to next step. If voltage and activation are
okay. Test is complete. Perform ECM relearn procedure. See TEST DRIVE RELEARN
PROCEDURE .
7.
wiring, power and ground supplies are okay. See ENGINE PERFORMANCE in
SYSTEM WIRING DIAGRAMS article in ELECTRICAL and ECM GROUND &
VOLTAGE SUPPLY .
2003 Volkswagen New Beetle GLS
2001-2003 ENGINE PERFORMANCE Self-Diagnostics - 2.0L - Beetle, Golf & Jetta (Engine Codes AVH & AZG)
Helpmelearn Repair Manuals
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