Porsche Frequently Asked Questions

Common Porsche Problems

Check Engine Light or running rough? Here you will find some answers to the most frequently diagnosed Porsche problems. We do not recommend you assume that the answer here directly relates to your Porsche. And, you should know that often third parties will misdiagnose a car for what appears to be similar problems or related diagnostic codes.

Diagnosing Porsche Problems

One of the most common misdiagnosis is where a customer believes they need a new catalytic converter because a well known parts store told them they have an O2 sensor code setting off a Check Engine Light! This can be a very expensive and time consuming Porsche mistake. Accurately diagnosing a Porsche problem requires more than just reading codes from an onboard computer.

Over the years we have heard and seen first hand the results of bad diagnosis, bad business practices or a simple lack of experience. You can read about the most recent and some of our all time favorites in our Horror Stories Section.

Below you will find answers to some of the more common Porsche problems and potential solutions. Please be cognizant of the fact that you have one check engine light and hundreds of reasons why it could be triggered.

OIL LEAKS AND OR BURNING OIL SMELL: Oil leaks can have a number of common different sources on Porsche vehicles. Some of the most common include valve cover gaskets and spark plug seals, but the most common and potentially destructive is the rear main seal. A leaking rear main seal shows in the center of the engine trans area. The leaking seal will destroy a clutch in a manual car very quickly. Vehicles that are stored often display a leak from the seal during storage or at the initial startup in the spring. The seal needs the heat of driving to seal efficiently, so in some circumstances the leak can slow. Replacing the seal requires the removal of the transmission.
LOW OR NO BATTERY POWER: Porsches are often garage queens and not driven as much as they could be. During any down period the car will continue to use some battery power - usually more than would be expected from similar vehicles. This can very quickly lead to a flat battery. Losing battery power resets a number of systems and can cause unnecessary headaches. We recommend you use a battery maintainer any time you store or do not drive the car for an extended period - 2 weeks or more.
CHECK ENGINE LIGHT: There are many causes of a Check Engine Light on Porsche vehicles. One of the most common for the 6 cylinder engines is a failure in the O2 and MAF systems. Commonly front O2 sensors will fail and cause the MAF to attempt to compensate. Commonly this results in many folks just replacing the front O2 sensors. Within a few hundred miles the light is back on. This is caused by the MAF failing. The recommended solution is to replace both the MAF and O2 sensors.
CLUTCH PEDAL IS HEAVY - TURBO 911: This is a common problem with manual transmission 911 Turbos. If you experience a very heavy clutch pedal before you start the engine, the common and likely cause is the pressure accumulator. This is a device designed to retain the hydraulic pressure necessary to operate the clutch after the engine has been stopped. In many circumstances the device will begin to leak the pressure back into the system and not function when called upon prior to startup. It is common practice to replace the clutch slave cylinder at the same time as replacing the pressure accumulator. The slave cylinder is often damaged or at least has its expected life shortened after the accumulator has failed.
HEAVY GEAR CHANGES AND CLUCKING SOUNDS - CAYENNE: Many Porsche Cayenne owners experience a heavy downshift from the transmission. In many circumstances this can be accompanied by much louder gear changes and clunking from the transmission. The problem is often mis-diagnosed as a physical failure in the transmission itself when the more likely cause is in fact the valve body assembly within the transmission. usually, replacing the valve body saves the transmission and returns normal smooth gear shifts.
LEAKING COOLANT - CAYENNE: What started out as a good idea, quickly turned into a potential nightmare. Running plastic coolant pipes underneath the intake manifold on a Porsche Cayenne seems like a reasonable idea, until you realize those pipes are prone to leaking. Once the leak starts it quickly speeds to a point where large clouds of steam can be seen billowing from under the hood. There is an update kit available to permanentely fix this problem and change those plastic pipes to metal ones. If your Cayenne has not been updated, it will need to be at some point in the future. If you are thinking of purchasing a used Cayenne, check this update has been completed prior to purchase.
NO START - CAYENNE: It is common to experience a no start situation on a Porsche Cayenne. Turn the key and the car will crank and crank and not start. There are a number of potential causes, but the most common is a failed fuel pump. The trick of course is to know which one of the 2 pumps has failed - commonly both are replaced at the same time.
METAL SHAVINGS IN OIL - 996: In the event you see metal shavings in the oil filter, see our page on Porsche Engine Building.
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CHECK ENGINE LIGHT AND WHITE SMOKE: A failure of the air-oil separator is often accompanied by large amounts of white smoke exiting the vehicle's exhaust and a generally poor running engine. You may also experience a check engine light. The separator is responsible for collecting residual gases and vapors contained inside the crankcase and funneling them back into the intake manifold where they can be burned in the combustion chamber. When the separator fails, oil is sucked into the combustion area and causes the white smoke. Oil passing through the combustion process can do significant damage not least of which is the failure of performance in catalytic converters.
KEY STUCK IN IGNITION AND WIPERS WONT WORK: This is a common problem on 996 and Boxster vehicles. A failure in the ignition lock mechanism causes the key to become sticky or difficult to remove. If you experience this have the car examined ASAP. At some point soon the key will not come out of the ignition and you will be left stranded. Replacing the ignition lock cylinder is straight forward and does not require a new key.
CLUNCKING NOISE IN DRIVELINE ON CAYENNE: On many Porsche Cayennes owners begin to complain of clunking from the driveline during acceleration. The cause of the noise is often premature Drive Shaft Support failure and is a direct result of too much continuous stress imposed upon the rubber in the mount. This is more the product of the Drive Shaft design than the quality of the rubber material in the mount. Unfortunately, by merely replacing the Bearing Support with another factory rubber mount you can expect much of the same results in the near future. Rennology uses an aftermarket fix that is considerably less expensive than replacing the factory mount and provides a much longer term solution.