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Volkswagen New Beetle. Manual - part 1860

connector terminal No. 1 to fuel pump relay (J17) harness connector, see appropriate WIRING
DIAGRAM under ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS. 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. 1 and 2 of HO2S harness connector. See Fig. 23 . 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 0-12 volts. Turn ignition off. If voltage and/or activation is not okay, go to next step. If
voltage and activation are okay, erase DTC memory. Test is complete. Perform ECM relearn procedure.
See TEST DRIVE RELEARN PROCEDURE .

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. 23 . 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 .

NOTE:

Before replacing ECM check HO2S control signal. See DTC P0136/16520,
DTC P0137/16521 & DTC P0138/16522 . If HO2S signal is not within
specifications it may set a DTC for HO2S heater malfunction.

2003 Volkswagen New Beetle GLS

2002-2003 ENGINE PERFORMANCE Self-Diagnostics - 1.8L Turbo

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Fig. 22: Identifying Heated Oxygen Sensor Terminals - Downstream TWC
Courtesy of VOLKSWAGEN UNITED STATES, INC.

2003 Volkswagen New Beetle GLS

2002-2003 ENGINE PERFORMANCE Self-Diagnostics - 1.8L Turbo

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Fig. 23: Identifying Heated Oxygen Sensor Harness Connector Terminals - Downstream TWC
Courtesy of VOLKSWAGEN UNITED STATES, INC.

DTC P0101/16485, DTC P0102/16486 & DTC P0103/16487

Code Definition

DTC P0101/16485: MAF Sensor (G70) - Implausible Signal

DTC P0102/16486: MAF Sensor (G70) - Voltage Signal To Low

DTC P0103/16487: MAF Sensor (G70) - Voltage Signal To High

Test Requirements

Ensure all fuses are okay, battery voltage is at least 11.5 volts, all electrical accessories are off, A/C is off.
Engine is mechanically sound. Ensure no exhaust system leaks exist. 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,

2003 Volkswagen New Beetle GLS

2002-2003 ENGINE PERFORMANCE Self-Diagnostics - 1.8L Turbo

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Page 64

selector lever must be in park or neutral with parking brake set.

Test Procedure

1. Inspect air induction system for leaks. Check air filter for blockage. 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.

Using scan tool, check air mass drawn in by engine. Air mass should be 2.0-4.5 grams/second at idle. If
air mass reading is okay, go to next step (voltage supply for MAF sensor must be checked). If air mass
reading is not okay, go to step 6 .

3. Turn ignition off. Disconnect MAF sensor 5-pin connector. Using DVOM, measure voltage between

MAF sensor 5-pin connector, terminal No. 2 and ground. See Fig. 24 . Start engine and idle. Voltage
should be 11-15 volts. If voltage is okay, go to step 5 . If voltage is not okay, go to next step.

4. Turn ignition off. Repair wiring from MAF sensor 5-pin connector, terminal No. 2 and fuel pump relay

(J17). See appropriate WIRING DIAGRAM under ENGINE PERFORMANCE in SYSTEM WIRING
DIAGRAMS. After repairs, erase DTC memory. Verify repair. Test is complete. Perform ECM relearn
procedure. See TEST DRIVE RELEARN PROCEDURE .

5. Turn ignition on. Using DVOM, check voltage between MAF sensor 5-pin connector, terminal No. 4 and

ground. See Fig. 24 . Voltage should be 4.5-5.5 volts. If voltage is okay, go to next step (further circuit
tests are required). If voltage is not okay, go to next step.

6. Turn ignition off. 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 the following MAF sensor (G70) connector terminals and test box
sockets. See Fig. 24 .

MAF sensor harness connector terminal No. 3 and test box socket No. 27.

MAF sensor harness connector terminal No. 4 and test box socket No. 53.

MAF sensor harness connector terminal No. 5 and test box socket No. 29.

Resistance should be a maximum of 1.5 ohms for each reading. If resistance measurements are okay, go
to next step. If any resistance measurement is not okay, repair circuit(s) as necessary. After repairs, erase
DTC memory. Verify repair. Test is complete. Perform ECM relearn procedure. See TEST DRIVE
RELEARN PROCEDURE .

7. Using DVOM, check wiring in MAF sensor 5-pin connector for short circuit to one another, short circuit

to ground, and short circuit to B+. Repair as necessary. After repairs, erase DTC memory. Verify repair.
Test is complete. Perform ECM relearn procedure. See TEST DRIVE RELEARN PROCEDURE . If
circuits are okay, go to next step.

8. If all wiring, voltage checks, and grounds are okay, and DTC P0101/16485, DTC P0102/16486 or DTC

P0103/16487 return, replace faulty MAF sensor (G70). After repairs, erase DTC memory. Verify Repair.
Test is complete. Perform ECM relearn procedure. See TEST DRIVE RELEARN PROCEDURE .

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2002-2003 ENGINE PERFORMANCE Self-Diagnostics - 1.8L Turbo

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