Before testing separate components or systems, perform preliminary inspection. Since many computer-controlled and monitored components set a trouble code if they malfunction, also perform procedures in G - TESTS W/ CODES article in the ENGINE PERFORMANCE Section.

NOTE: Testing individual components does not isolate shorts or opens. Perform all voltage tests using a Digital Volt-Ohmmeter (DVOM) with a minimum 10-megohm input impedance unless otherwise instructed in test procedure. Use ohmmeter to isolate wiring harness shorts or opens.

ELECTRICAL COMPONENT LOCATIONS

Component

Location

Circuit Breakers

⁽¹⁾ In Passenger Footwell, In Electronic Box

Closed Throttle Position (CTP) Switch

Part Of TP Sensor

Component Connectors

See Fig 1

Camshaft Position (CMP) Sensor

Rear End Of Left Cylinder Head

Crankshaft Position (CKP) Sensor

On Left Side Of Cylinder Block

Data Link Connector (DLC)

Behind Left Side Of Dash

Electronic Box

In Passenger Footwell, Under Glove Box

Elect. Control Module (ECM)

Passenger Footwell, In Electronic Box

EGR Control Solenoid Valve

In Right Rear Corner Of Engine Bay

EGR Temperature Sensor

Left Rear Corner Of Engine, On EGR Valve

Engine Coolant Temperature (ECT) Sensor

To Rear Of Left Cylinder Head, On Coolant Pipe

Engine Speed Sensor

On Left Side Of Transmission Bellhousing

EVAP Control Solenoid Valve

In Right Rear Corner Of Engine Bay

Fuel Pump Relay

Under Left Side Of Instrument Panel, In Fuse/Relay Block

Fuses

In Fuse/Relay Block

Fuse/Relay Block

Behind Left Side Of Instrument Panel

Idle Air Control (IAC) Valve

Right Rear Corner Of Intake Manifold

Intake Manifold Change-Over (IMCO) Valve Control Solenoid

In Right Rear Corner Of Engine Bay

Kickdown Switch

On Throttle Body

Knock Sensor No. 1

On Right Cylinder Bank, Under Intake Manifold

Knock Sensor No. 2

On Left Cylinder Bank, Under Intake Manifold

Mass Airflow (MAF) Sensor

In Air Intake Hose

Power Output Stage

On Right Side Of Engine Bay Firewall

Throttle Position (TP) Sensor

On Throttle Body

⁽¹⁾	Circuit breakers are identified by color: fuel injectors (Red), ignition coil (Yellow), mass airflow sensor (Black) and oxygen sensor (Brown).

Fig 1: Locating Electrical Component Connectors

Courtesy of AUDI OF AMERICA, INC.

When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

• You smell fuel, burning insulation, or see smoke.

• Brakes feel soft, pull hard to one side, or make grinding noises.

• The engine overheats, stalls repeatedly, or misfires under load.

• You are missing required tools, torque specs, or safe lifting equipment.

• You are not confident in the next step or safety outcome.

Safety Warning

Engine Controls - System/Component Tests: Introduction

Use the Manual With the Right Hardware

When to See a Mechanic