Got Problems With The BMW / GM 4L30-E Transmission? We Show You How To Fix Them!

Posted by on Tuesday, December 4th, 2012

The 4L30-E transmission is a 4 speed automatic transmission used in light duty, rear wheel drive vehicles. It was first used in the 1990 BMW 525i and was used up through 2001 in a large variety of makes and models. Among them where the Chevy Omega, Honda Passport, Acura SLX, Cadillac Catera, Isuzu  Amigo, Isuzu Rodeo and the Isuzu Trooper. The 4L30-E transmission was built at the GM facility in Strasbourg, France. While generally a pretty reliable transmission it is still prone to certain problems. Here is a list of common problems.

525i BMW with 4L30-E transmission


1) Transmission goes into limp mode. Limp mode is a way the computer controls the transmission in the event it senses something is wrong. The transmission receives input from a variety of sensors. Some of the sensors are on the motor and some are on the transmissions itself.  When in limp mode, you usually can only go into one forward gear. There are many reasons a transmission might go into limp mode. Bad sensor, bad or broken wire, low line pressure, valve body problems, band/clutches wearing out and more.

2) The transmission has a solenoid failure. The solenoid control many functions in the transmission. They move the valves in the valve body after receiving an electrical signal from the computer. Common causes for failure include broken wires, corrosion in the solenoid, weak springs, electrical shorts and overheating.

4L30E Automatic Transmission


3) The transmission pops out of drive. A common cause for this problem stems from the transmission being low on fluid. A dirty or worn gear selector switch can also be the cause of this problem.

4) The transmission suffers from a harsh 2-3 shift. Once again the fluid level being too low can cause this problem.  Another problem might be that the 2-3 shift solenoid is failing. You should also take a look at the TCM and the range sensor to make sure they are operating properly.

5) The transmission is suffering from computer related issues. The computer may be defective but they don’t fail too often. In most cases you can unhook the battery, wait a couple minutes and hook it back up. This clears the computer of any faulty codes that are transmission related.

4L30E Automatic Transmission


6) The transmission will not shift out of 1st gear. Take a look at the range sensor and make sure it is functioning properly.  The same goes from the VSS (Vehicle Speed Senor). If either of these fail they may cause this problem.

So you ask, how I can prevent these problems?  While you can’t prevent all of them, here are a couple tips:

1) Change the fluid every 25,000 miles. Same goes for the transmission filter. Refilling the transmission can be a challenge. You might have to use a pump to get fresh fluid back into the transmission.

2) Make sure the range sensor is kept clean. I recommend removing and cleaning it every 30,000 miles. Use a special electric cleaning fluid and be sure to dry completely. Lube the sensor with dielectric lube, inspect seals and replace as necessary.

If buying a used car equipped with the 4L30-E, be sure to check for the problems listed above. If you already own a car with the 4L30-E transmission you can prevent a lotof problems by simply changing the transmission fluid and filter on a regular basis. With care the transmission should last a long time.

If the transmission fails I recommend you replace it with a re-manufactured unit, not one that was simply  rebuilt. The re-manufacturing process of the transmission restores the transmission to like-new condition and may also incorporate fixes for common problems.

A re-manufactured transmission will also include a much better warranty; three years compared to an average 90 days for a rebuilt transmission. As a bonus, in the rare event that a re-manufactured transmission fails within the warranty period, they will cover your R&R cost to replace your customer’s transmission. And remember, the companies that re-manufacture transmissions are very easy to contact. They are just a quick phone call or email away from helping you out.

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