Volkswagen New Beetle. Manual - part 1892

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. 64 .

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, or 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. Check Throttle Valve Control Module (TVCM - J338). See DTC P1171/17579, DTC P1172/17580 &

DTC P1173/17581 .

9. Check Accelerator Pedal Position Sensors (APPS 1 - G79) and (APPS 2 -G185). See DTC P1630/18038,

DTC P1631/18039, DTC P1633/18041 & DTC P1634/18042 .

10. If TVCM - J338, APPS 1 - G79 and APPS 2 - G185, voltage checks, wiring and grounds are okay and

DTC P1141/17549, DTC P1142/17550 or DTC P1143/17551 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 .

2003 Volkswagen New Beetle GLS

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

Helpmelearn Repair Manuals

Wednesday, December 14, 2005 8:44:46 AM

Page 190

Fig. 64: Identifying Mass Airflow Sensor (G70) Harness Connector Terminals
Courtesy of AUDI OF AMERICA, INC.

DTC P1149: HO2 SENSOR (G39) UPSTREAM TWC - IMPLAUSIBLE SIGNAL

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).

Test Procedure

1. Check air induction and secondary air injection system for leaks. Check air filter for blockage. If no air

leaks are found and air flow is unrestricted, 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 .

NOTE:

Upstream HO2S (G39) control signal activation may only occur above 1500
RPM.

2003 Volkswagen New Beetle GLS

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

Helpmelearn Repair Manuals

Wednesday, December 14, 2005 8:44:46 AM

Page 191

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 G20
control signal activation. HO2S control signal should be activated. Use scan tool to check upstream
HO2S readiness. HO2S should be operationally ready. Observe scan tool in upstream HO2S heater
activation test mode. Heater should be on. If HO2S heater is on, activation and readiness checks are okay.
Go to next step (further testing is needed). If HO2S heater is off, or if HO2S activation or readiness
checks are not okay, check HO2S heater. See DTC P0130/16514 & DTC P0135/16519 .

Using scan tool, check upstream HO2S learned values at idle and part throttle. Learned values should be
negative 10 to positive 10 percent (0.3 to 0.7 volt) at idle and part throttle. If learned values are okay, go
to next step. If learned values are not okay and show a lean signal, go to step 6 . If learned values are not
okay and show a rich signal, go to step 7 .

4. Using scan tool, check upstream HO2S control signal switching. Values should be negative 10 to positive

10 percent (0.3 to 0.7 volt) at idle and part throttle and must switch a minimum of 2 percent (0.1 volt). If
test values are not as specified and faulty wiring is suspected, go to step 11 . If test values are not as
specified and wiring is not suspect, go to next step. If test values are okay, erase DTC memory. Perform
ECM relearn procedure. See TEST DRIVE RELEARN PROCEDURE .

5. Test drive vehicle (to burn HO2S clean) and retest system. If test values are okay after test drive, go to

next step. If test values are not okay after test drive, replace upstream HO2S. After repairs, erase DTC
memory. Verify repair. Test is complete. Perform ECM relearn procedure. See TEST DRIVE
RELEARN PROCEDURE .

6. Check downstream HO2S control. See DTC P0136/16520, DTC P0137/16521 & DTC P0138/16522 . If

downstream HO2S control is okay. Go to next step.

7. Check for gasoline fouled engine oil. Change engine oil as necessary. Check fuel pressure and fuel

pressure regulator. See FUEL SYSTEMS in appropriate SYSTEM & COMPONENT TESTING article. If
fuel pressure is okay, go to next step. If fuel pressure 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 .

8. Check fuel injector volume (possible blocked or leaking injector). See FUEL SYSTEMS in appropriate

SYSTEM & COMPONENT TESTING article. If fuel injector volume is okay, and fuel injectors do not
leak more than 2 drops per minute each, go to next step. If fuel injector volume is not okay and /or any
fuel injectors leak more than 2 drops per minute each, repair as necessary. After repairs, erase DTC
memory. Verify repair. Test is complete. Perform ECM relearn procedure. See TEST DRIVE
RELEARN PROCEDURE .

9. Check to see if EVAP canister purge valve (N80) is stuck in the open position. If EVAP canister purge

valve is okay go to next step. If EVAP canister purge valve is not okay, repair as necessary. See DTC
P0440/16824 & DTC P0441/16825 . After repairs, erase DTC memory. Verify repair. Test is complete.
Perform ECM relearn procedure. See TEST DRIVE RELEARN PROCEDURE .

10.

NOTE:

Operating range of upstream HO2S is negative 25 to positive 25 percent
when using Scan Tool VAG 1551/1552 or VAS 5051. Specified range of
upstream HO2S is negative 10 to positive 10 percent when using Scan
Tool VAG 1551/1552 or VAS 5051. In testing procedures negative 10 to
positive 10 percent specification is allowed to vary slightly.

2003 Volkswagen New Beetle GLS

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

Helpmelearn Repair Manuals

Wednesday, December 14, 2005 8:44:46 AM

Page 192

Check MAF sensor (G70). See DTC P0101/16485, DTC P0102/16486 & DTC P0103/16487 . If MAF
sensor is okay, go to next step. If MAF sensor 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 .

11. Turn ignition off. For Passat, see Fig. 18 . For all other models. Raise vehicle and remove HO2 sensors

protective cover and disconnect upstream HO2S (G39) harness connector (black 6-pin), see Fig. 19 . Go
to next step.

12. 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 upstream HO2S connector terminals and test box
sockets. See Fig. 21 .

Upstream HO2S connector terminal No. 1 and test box socket No. 70.

Upstream HO2S connector terminal No. 2 and test box socket No. 71.

Upstream HO2S connector terminal No. 5 and test box socket No. 51.

Upstream HO2S connector terminal No. 6 and test box socket No. 52.

Resistance should be a maximum of 1.5 ohms for each reading. Check wiring in upstream HO2S 6-pin
harness connector for short circuits to one another. If resistance measurements are okay and no short
circuits exist. Replace upstream HO2S. After repairs, erase DTC memory. Verify repair. Test is complete.
Perform ECM relearn procedure. See TEST DRIVE RELEARN PROCEDURE . If any resistance
measurement is not okay, or a short circuit exists, repair circuit(s) as necessary. After repairs, erase DTC
memory. Verify repair. Test is complete. Perform ECM relearn procedure. See TEST DRIVE
RELEARN PROCEDURE .

DTC P1171/17579, DTC P1172/17580 & DTC P1173/17581

Code Definition

DTC P1171/17579: Angle Sensor 2 (G188) For Throttle Valve Drive - Implausible Signal

DTC P1172/17580: Angle Sensor 2 (G188) For Throttle Valve Drive - Signal Too Low

DTC P1173/17581: Angle Sensor 2 (G188) For Throttle Valve Drive - Signal Too High

Circuit/Component Description

Throttle Valve Control Module (TVCM - J338) is located on throttle body. Throttle valve drive angle sensors
and are located in TVCM (J338). ECM monitors throttle valve drive angle sensors for throttle valve position.
ECM calculates throttle position based on percentage values sent by throttle valve drive angle sensors. Throttle

NOTE:

If MAF sensor (G70) malfunctions, a DTC for MAF sensor should be
present in ECM memory.

NOTE:

If a test ends with ECM replacement. Before replacing ECM be certain that, all
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

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

Helpmelearn Repair Manuals

Wednesday, December 14, 2005 8:44:46 AM

Page 193

Content .. 1890 1891 1892 1893 ..