Fuel pump relay Skoda Octavia Tour: Diagnostics, troubleshooting and replacement

Starting the engine on vehicles of the family Skoda Octavia Tour directly depends on the health of the fuel system, namely on the power supply to the fuel pump. Often, owners are faced with a situation where the engine does not start, the starter turns vigorously, but the sound of the pump in the tank is not heard. In most cases, the root of the problem lies in the control element of the circuit - fuel pump relay.

On the platform Octavia Tour, which is based on VAG units from the late 90s and early 2000s, the electrical wiring and switching elements are subject to significant stress. The relay is a key link that supplies voltage to the pump only when the engine is started and running. If this component fails, the car becomes immobilized, and without the proper knowledge, finding the cause of the breakdown in a service center may take extra time.

In this article, we will analyze in detail the design features of the relay, indicate its exact location in the mounting block, and also provide step-by-step instructions for diagnostics and replacement. You'll learn how to distinguish between a faulty relay itself and problems with the wiring or crankshaft sensor, so you can avoid unnecessary costs for unnecessary parts.

Location and identification of the relay on the Skoda Octavia Tour

First you need to determine exactly where the required component is located. On Skoda Octavia Tour with the A4 body (and its modifications), the mounting block is located on the left side of the dashboard, under the plastic cover. When you open the hood or look into the interior on the driver's side, you will see the fuse and relay box.

The fuel pump relay on most engines of this generation (including 1.6 MPI and 1.8 Turbo) is marked J17 or has a serial number depending on the year of manufacture. It is often located in the top or middle row, next to the starter relay and cooling fan relay. Visually, it is a black or brown plastic cube with inscriptions on the end.

Do not confuse this device with other relays in the block, as they may be identical in appearance. Key Feature - this is the connection diagram, which may differ for engines with multipoint injection and for turbocharged versions. Be sure to check the diagram on the inside of the mounting block cover so as not to remove the relay responsible for ABS or window lifters.

Sometimes the manufacturer uses relays with different number of contacts (4 or 5), but the functionality of them is similar. It is important to pay attention to the color marking of the body, if it is present. In some configurations, the relay can be hidden under additional plugs that require careful removal by a plastic blade.

Typical symptoms of a malfunction

To understand that the problem is in the relay, you can by a number of characteristic signs that appear suddenly. The most obvious symptom is the absence of a sound “bug” of the pump when turning the key into position. ON (ignition activation). In good condition, the pump must create pressure in the highway for a split second, emitting a characteristic hum from under the rear seat.

Another sign is a situation when the engine starts normally, but stops immediately after starting work. This may indicate that the relay does not keep the contacts closed after starting, losing the signal from the relay. crankshaft position sensor. It is also possible to appear interruptions in the operation of the engine on the go, especially under load, when the current consumption of the pump increases.

Sometimes the problem manifests itself at high engine temperature. The relay can work properly in a cold state, but refuse after warming up due to expansion of contacts or degradation of the internal coil. In such cases, the car can start in the morning, but not start after parking on a hot day.

• 🔊 Complete absence of sound of the fuel pump when the ignition is turned on.
• ⛽ The engine starts and immediately stops after 1-2 seconds.
• 🌡️ Difficulty starting only on a hot engine.
• ⚡ Intermittent operation of the motor at idle speeds or during acceleration.

Diagnostics: how to check a relay without replacement

Before running to the store for a new detail, it is worth conducting a simple diagnosis to exclude false positives. The fastest way is the method of relocation. Find a relay in the block that has a similar marking and circuitry (e.g., relay). headlights or windshield wiper), and change them. If the pump is running after replacement, then the old relay is to blame.

A more accurate method requires a multimeter. Take off the relay and look at his contacts. Usually, there is a diagram on the case, where the numbers of the conclusions are indicated. The integrity of the control coil winding must be checked. Multimeter chips are put on the conclusions of the coil (most often these are pins). 85 and 86), and the resistance must be between 60 and 90 Ohms.

Also check the power contacts. At rest (without applying voltage to the coil) power contacts (usually 30 and 87) shall be open. When applying a voltage of 12 volts to the coil, a clear click should be heard, and the contacts should close, showing zero resistance. If there is no click or resistance is high, the relay is faulty.

It is important to check the socket itself in the mounting unit, where the relay is inserted. Oxidation of contacts or their melting due to poor contact often mimics relay failure. Use it. contact spray Cleaning the nests before installing a new part. If the nests are loose, contact will disappear when vibrating.

Replacement process and installation nuances

Replacing the relay with Octavia Tour It does not require special tools and takes no more than five minutes. However, to avoid damage to plastic fasteners, be careful. First, remove the negative terminal from the battery to exclude short circuits when carelessly moving.

With a plastic blade or tweezers, gently tuck the body of the relay and pull it out of the seat. Do not pull the wires if they are connected, and do not use excessive force so as not to break the locks on the board. After extraction, visually inspect the contacts for soak or oxidation.

The new relay must have the same marking. Check the part catalog number carefully, as different suppliers may have been used in different markets (e.g., the number of the parts in the list) Continental, Hella or Siemens). Make sure the location of the legs matches the pattern. Insert the relay until the characteristic click so that it sits tightly.

• 🛠️ Use only original or certified analogues (VAG, Bosch).
• 🔌 Check the integrity of the legs before installation, they should not be bent.
• 🔋 Before work, turn off the battery's negative terminal for safety.
• 🧼 Clear the seat of dust and possible traces of oxidation.

Reasons for relay failure

A gasoline pump relay is a mechanical device with movable contacts that is subject to natural wear. The main cause of breakdown is electrical arc discharge during switching of the load. Each time the pump is turned on, the contacts are microscopic burnt down, which over time leads to their destruction and an increase in transient resistance.

The second important factor is overheating. Installation blocks in cars Skoda located in an area where heat from the engine or wiring can accumulate. Long-term operation at high temperatures leads to degradation of the plastic case and soldering inside the relay. This is especially true for engines. 1.8 Turboworking in heavy duty regimes.

Unstable voltage in the onboard network also plays a role. Voltage surges caused by a faulty generator or short circuits in the wiring can cause the control coil to break down. The relay will no longer respond to the signal from electronic control unit (ECU).