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Typical automatic transmission problems and their causes

When problems arise with an automatic transmission, it does not always happen suddenly. Some symptoms creep in gradually and if they go unnoticed, an initially sometimes quite simple cause can develop into a full-blown defect. How to recognize typical problems with automatic transmissions and what to do about them service To find out how to do this, read this article. We have also listed the most common problems and symptoms that we have to deal with in our workshop during repairs.

A automatic transmission is a comfortable thing: you put in gear "D" and no matter what speed you are traveling at, the right gear is automatically selected. However, this comfort can also have its problems: Since you don't have to concentrate on anything further behind the steering wheel than the drive itself, one or the other symptom can go unnoticed during the automatic gear change. In a vehicle with a manual transmission, problems can draw attention to themselves a little more clearly - for example, when individual gears are difficult or hard to engage, the clutch slips or the manual transmission as a whole is jittery.

How do problems become noticeable?

With an automatic transmission, however, the problems are not dissimilar, as you can read in the numerous contributions in relevant forums on the Internet. Typical here are, for example:

  • Jerky, rough gear changes
  • Delayed start
  • Automatic switching is delayed when the engine is cold
  • Severe hum or vibration
  • Some gears are no longer engaged
  • Metallic grinding or grinding noises
  • High speeds without propulsion
  • Burned smell
  • No more drive, neither forwards nor backwards

It is becoming increasingly difficult for the layman as well as for some auto repair shops to find the real causes of problems with automatic transmissions. One of the reasons for this is the large number of gearbox variants that are now on the market. They are technically advanced, significantly more complex than older types of automatic transmissions, and many are controlled by what is known as an EGS, an electronic transmission control unit. All these circumstances make it difficult for non-specialized repairers to get a reliable diagnosis and repair perform. Quite a few automatic systems that are installed in certain car brands, however, often stand out with their own typical symptoms.

For example, here would be the Multitronic to be mentioned in vehicles from Audi. In some cases it can happen that the positive connection in reverse gear is delayed and only established above a certain engine speed, which makes slow maneuvering impossible. Other types of transmission, such as the direct shift transmission (DSG) - installed in VW models from the Golf to the Touareg - can be noticed while driving due to unpleasant noises and vibrations. Sometimes you can read hard shocks when changing gears in forums AF40 by Aisin Warner, which is used in the Opel Insignia. Regardless of the anomaly, automatic drivers should not hesitate to visit the nearest professional workshop. Here we know the characteristics of automatic transmissions from various manufacturers very well, so that the cause can be specifically identified.

A common cause: the transmission oil

In the case of some symptoms, for example worsened driving and shifting behavior, the cause is not infrequently due to individual wear parts or a defect in the torque converter. However, it is not uncommon for the cause of problems to be found in the oil of the automatic transmission, especially with shift bumps or shift delays. In addition to a low water level, the age of the oil in particular can cause problems with the automatic system.

Many manufacturers speak of a "lifetime" or "lifetime filling" - then you can't get that Automatic transmission oil change and save the cost of it? No! Especially not if you often drive short distances. Because the transmission oil also ages over time. Depending on the mileage, driving style or external influences, it loses viscosity and lubricity and impurities, foam or oil sludge can form in the automatic transmission.

In this way, proper lubrication cannot be achieved and wear increases sharply - so much that it can mean the end of the automatic transmission. The change interval depends on many individual factors, but if you want to be on the safe side, check the oil level from 50,000 kilometers or have the oil change carried out every 60,000 to 80,000 kilometers.

Another way to prevent gearbox damage is this Gear flushingwhich is carried out with a special flushing device. While only about half of the oil can be changed for technical reasons when changing the transmission oil, thanks to the transmission flushing it is possible to completely renew the entire automatic transmission oil and also to completely flush the transmission oil lines.

Automatic transmission problems and the most common causes

If the automatic transmission slips or it jerks and jerks when stationary or when changing gears, the cause may be damage to the torque converter or the clutch plates. It is not uncommon, however, to have a slide switch problem.

When driving, does it only go ahead in reverse? Or is the reverse gear slipping? Then it is based on mechanical damage to the forward clutch. However, only the clutch plates could be worn.

If the automatic transmission can no longer be shifted or is difficult to shift, if it blocks or no longer takes any gears, the selector lever module, the PRND switch or the brake light switch could be defective. However, there may also be internal mechanical gear damage.

Shifting hard when it is warm is a sign that there is a problem with the pressure. However, seals in the transmission could also be defective or there could be something wrong with the slide switch.

In the case of improper shifting or the shifting of the automatic transmission, the probability is high that the oil is already old - here a transmission oil flush or an automatic transmission oil change is advisable. However, the cause can also be due to the slide switch, a defect in the solenoid valve, the control unit or incorrect adaptation values ​​or the old software version.

If there is no longer any frictional connection, the car no longer drives and suddenly the drive is missing, there may no longer be a connection between the converter and the input shaft of the transmission - this could have been broken. It is not uncommon for the turbine wheel in the converter to be defective or for the oil pump to be damaged.

If the automatic transmission does not take on the gas or does not pull it properly, the cause could be converter damage. Wear of the clutch plates in the transmission would also be possible.

For example, if the automatic transmission whistles when accelerating or makes other unusual noises while idling or while driving, the problem could be a converter failure, differential failure, bearing failure, or planetary damage in the transmission.

If the transmission simply shifts to N while driving, there may be a shift slide problem or a defect with the transmission control unit.

If the automatic transmission smells burnt, of rubber or characteristic of the clutch, then it may be that the transmission is losing oil, the transmission oil level is too high, the oil seal is leaking or the cause is a converter or oil pump damage.

If too much slip is noticeable in the automatic transmission in everyday life, this is an indication of wear on the clutch plates or the converter clutch.

If the gear changes are too early, the software version on the gearbox control unit should be checked. The adaptation data may be incorrect or the gearbox control unit is defective. Otherwise, a sensor error in other assemblies can also be responsible, e.g. B. in engine or ABS electronics.

If the transmission shifts down the gears too late or too late, this is probably due to a pressure problem or a defective shift slide.

If the automatic system suddenly switches to emergency mode, it may be due to an internal mechanical transmission fault, a problem with the transmission electronics or a defect in the speed sensor.

A tip from the automatic transmission specialist

Anomalies in the automatic transmission do not always have something to do with the automatic itself. Malfunctions can also occur if electrical components in other assemblies in your car malfunction (engine electrics, ABS, etc.). So it can be that even comparatively inconspicuous parts can cause problems.

An example: The signal from the brake light switch is used by the gearbox control unit to release the selector lever lock. The switching times, however, are calculated by the gearbox control unit using the throttle valve potentiometer signal from the engine. So it is definitely worthwhile to turn your attention to other areas of the automobile if the automatic system should cause problems

The solution to automatic transmission problems: repair instead of complete replacement

If the automatic system fails or causes problems, both independent vehicle workshops and the authorized workshops of the individual manufacturers are faced with a major challenge: the quick and at the same time inexpensive removal of the defect. Because it is not uncommon to solve the problem with the automatic simply by replacing the entire transmission. This is relatively quick, but it goes without saying that a new automatic transmission is quite expensive.

As already mentioned, an automatic transmission oil change can be sufficient if it is not possible to drive faster despite the high engine speed. Replacing a torque converter, on the other hand, is the solution if the vehicle cannot be driven forwards or backwards. Whatever the fault, the clear advantage of a repair is the cost factor. Only the parts that are actually affected by a defect are exchanged here - of course, this requires a specific error diagnosis. Specialized specialist workshops that do nothing other than repair and overhaul automatic transmissions every day know the typical problems, have the right spare parts in stock and can therefore eliminate the cause quickly and inexpensively.