Idling sensor for Volkswagen Passat B3: do-it-yourself diagnostics and replacement
Tips for motorists

Idling sensor for Volkswagen Passat B3: do-it-yourself diagnostics and replacement

There are a huge number of small elements in the design of any car. Each of them in one way or another affects the operation of the car as a whole, without any of these small mechanisms, the operation of the car will be impossible or difficult. The idle speed sensor deserves special attention of drivers. This is a small device, the performance of which determines whether the driver can start the engine at all.

Idling sensor "Volkswagen Passat B3"

The idle sensor in the design of the Volkswagen Passat B3 is responsible for the stability of the power unit in idle mode (hence the name). That is, in those moments when the driver starts the engine in order to warm up or in minutes of stopping without turning off the engine, it is this sensor that provides smoothness and stability of revolutions.

Technically speaking, the idle speed sensor on the Passat models cannot be considered a sensor in the usual sense of this term. The DHX is a performance device that regulates the supply of fresh air, and does not work on reading and transmitting data, like a typical sensor. Therefore, almost all Volkswagen Passat B3 drivers call this device an idle speed controller (IAC).

Idling sensor for Volkswagen Passat B3: do-it-yourself diagnostics and replacement
The engine idling is controlled by the idle sensor, otherwise called the regulator

In Passat B3 cars, the idle speed sensor is located in the engine compartment. The sensor body is attached with two screws to the throttle body. This position next to the engine is due to the fact that the IAC must regulate the air supply as accurately as possible to create a fuel-air mixture, and the easiest way to do this is directly next to the engine.

Thus, the main task of the IAC is considered to adjust the air supply at idle, so that the motor receives the necessary resources to operate at low speeds.

Idling sensor for Volkswagen Passat B3: do-it-yourself diagnostics and replacement
The sensor is replaced on the motor housing

IAC device

The design of the idle speed controller on Volkswagen Passat vehicles is based on one basic element - a stepper motor. It performs an important function - it moves the actuator to the distance that is currently necessary for high-quality performance of the work.

In addition to the motor (electric motor), the IAC housing contains:

  • movable stem;
  • spring element;
  • gaskets;
  • needle (or valve).

That is, the motor moves the stem, at the end of which there is a needle. The needle can close, overlap or additionally open the throttle valve. Actually, this determines the required amount of air for the operation of the motor.

Idling sensor for Volkswagen Passat B3: do-it-yourself diagnostics and replacement
The IAC contains only a few parts, but their incorrect installation or neglect of the distances between them make the device unusable.

The life of the idle speed control is usually determined by the vehicle manufacturer. In the case of the latest Volkswagen Passat models, this value is equal to 200 thousand kilometers. However, it is not uncommon for the IAC to fail for a number of reasons much earlier than the time specified in the manual.

Mono injection engine

Every Volkswagen Passat equipped with a single injection engine has been fitted with a VAG idle speed regulator No. 1988 051 133 since 031.

Monoinjection is a system in which the throttle valve plays the main role. It is this element that is designed to collect and dose air before it enters the combustion chamber. And the idle speed sensor VAG No. 051 133 031 should monitor this process. Accordingly, in the event of sensor breakdowns on engines with mono injection, the driver will not feel serious inconvenience, since the damper will still function normally.

Idling sensor for Volkswagen Passat B3: do-it-yourself diagnostics and replacement
On older versions of Volkswagen Passat B3, large-size control devices were installed

Injector engine

Things are a little different with Volkswagen Passat engines powered by an injector. The IAC is fixed on the throttle valve, which in general "controls" the operation of this mechanism. That is, if the sensor fails, then immediately troubles begin with idle and high engine speeds.

Idling sensor for Volkswagen Passat B3: do-it-yourself diagnostics and replacement
More modern versions of the "Volkswagen Passat B3", running on injection engines, are available with a cylindrical IAC

Video: the principle of operation of the IAC

Problems with idle speed sensors (IAC) on the Volkswagen Passat B3

What can the incorrect operation of the IAC or the failure of the device lead to? The complexity of this problem lies in the fact that if the IAC breaks down, then the signal to the driver is not sent to the control panel (as other sensors do). That is, the driver can find out about a breakdown only by those signs that he himself notices while driving:

A large number of drivers are interested in the question: what are all these problems connected with, why does the IAC fail before the stated date? The main reason for incorrect operation lies both in the wiring of the device and in severe wear of the stem or sensor spring. And if the problem with the wires is solved quickly (during a visual inspection), then it is almost impossible to determine the breakdowns in the case.

In this regard, the idle speed regulator on the Volkswagen Passat is difficult to repair. Repair work can be performed, but there is no guarantee that the device will be assembled correctly, since the position of each element is strictly defined. Therefore, in case of any problems with the speed, it is recommended to immediately replace this device.

How to extend the life of the idle sensor

Service specialists recommend that Volkswagen Passat B3 owners follow simple rules in order to maximize the service life of the IAC:

  1. Replace the air filter in a timely manner.
  2. When parked for a long time in winter, periodically warm up the engine in order to exclude the possibility of IAC sticking.
  3. Make sure that foreign liquids do not get on the idle speed sensor housing and on the throttle valve.

These simple tips will help to avoid rapid wear of the sensor mechanisms and extend its service life up to the manufacturer's declared 200 thousand kilometers.

DIY idle sensor replacement

In the event of a malfunction in the operation of the IAC, it will be necessary to replace it. This procedure is simple, so there is no point in contacting the service station specialists.

IAC is not cheap. Depending on the year of manufacture "Volkswagen Passat" and the volume of the engine, the device can cost from 3200 to 5800 rubles.

To complete the replacement, you will need:

Operating procedure

It is best to dismantle the IAC on a cold engine: this way there will be no risk of getting burned. Removing an old sensor and installing a new one takes several steps:

  1. Remove the negative terminal from the battery.
  2. Disconnect the loop of wires from the IAC case.
  3. Unscrew the screws securing the sensor.
  4. Pull the sensor itself out of the seat.
  5. Clean the joint from dirt and dust adhesion.
  6. Install a new IAC in the vacant slot, tighten the screws.
  7. The main task when installing the IAC is to provide a distance of 23 mm from the sensor needle to the mounting flange.
  8. Connect a loop of wires to it.
  9. Replace the negative wire to the battery terminal.

Photo gallery: do-it-yourself IAC replacement

Immediately after replacement, it is recommended to start the engine and check the correctness of work. If the engine runs smoothly at idle, then the new IAC has been installed correctly. For your own peace of mind, you can turn on the headlights and air conditioning at the same time - the speed should not "fall".

Idle adjustment

Quite often, the idle speed sensor can be "capricious" for the reason that the initial parameters of its operation have gone astray. In these cases, you can adjust the idle speed. IAC will become the main element of this work.

The adjustment procedure should be performed according to the algorithm:

  1. An adjusting screw is located on the engine throttle valve.
  2. If the engine speed jumps a lot when the car is idling, you need to slightly unscrew this screw towards you (no more than 0.5 turn).
  3. If the revolutions are stably low, insufficient, then you need to screw the adjusting screw into the damper.
  4. It is important to measure the distance between the IAC needle and the flange: it should not exceed 23 mm.

Video: detailed instructions for adjusting idle speed

I suffered for three years. Everything is simple. There is a bolt on the throttle. If the revs jump, then turn it up a little. If the revs stick, spin it. It can still loosen up on its own over time. Also, be sure to check all vacuum tubes for cracks. can air pass

Thus, it is impossible to repair the idle speed regulator with your own hands: it is much easier and faster (albeit more expensive) to replace it with a new one. If necessary, you can always adjust the operation of the idle systems: if you do it yourself, it will take some time to understand exactly how many revolutions it is better to unscrew the screw.

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