between terminals No. 1 and 2 of HO2S harness connector. See Fig. 16 . Reconnect scan tool (if
removed). Start engine and idle. Following scan tool manufacturer's instructions, use scan tool to check
HO2S (G130) heater activation. Observe scan tool in downstream 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.
Disconnect ECM harness connector, leave ECM disconnected from test box. Connect Test Box (VAG
1598/31) to ECM harness connector. See CONNECTING VAG TEST BOX . Using DVOM, check
resistance between HO2S harness connector No. 2 and test box socket No. 63. See Fig. 16 . Resistance
should be a maximum of 1.5 ohms. If resistance is not okay, repair as necessary. After repairs, erase DTC
memory. Verify repair. Test is complete. Perform ECM relearn procedure. See TEST DRIVE
RELEARN PROCEDURE . If resistance is okay, and all wiring is okay, replace faulty ECM. See
ENGINE CONTROL MODULE REMOVAL & INSTALLATION . Erase DTC memory. Verify
repair. Test is complete. Perform ECM relearn procedure. See TEST DRIVE RELEARN
PROCEDURE .
DTC P0170/16554, P0171/16555 & P0172/16556: FUEL TRIM
Code Definition
DTC P0170/16554
Fuel Trim - System Malfunction
DTC P0171/16555
Fuel Trim - Too Lean
DTC P0172/16556
Fuel Trim - Too Rich
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. Check air filter for blockage. If no air
NOTE:
Before replacing ECM check HO2S control signal. See DTC P0136/16522,
DTC P0137/16521 & DTC P0138/16522 . If HO2S control signal is not within
specifications it may set a DTC for HO2S heater malfunction.
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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