OBD-II Generic Error Code P2799: How to Fix It

Q: Can I drive my car with a P2799 code?

Short trips may be possible, but it is not recommended to drive for extended periods or tow with P2799 active. The auxiliary transmission fluid pump helps cool and circulate fluid under demanding conditions. If it is not operating correctly, your transmission can overheat and suffer serious internal damage. Have the fault diagnosed and repaired as soon as possible.

Q: What causes a P2799 code?

The most common causes include a short to voltage in the auxiliary pump control circuit wiring, a faulty or internally shorted auxiliary transmission fluid pump, a blown fuse or failed relay, corroded or damaged electrical connectors, or in rare cases a faulty powertrain control module (PCM). Wiring issues are the most frequent culprit.

Q: Is P2799 a serious transmission problem?

P2799 is rated as a medium severity code. It does not always mean your transmission is damaged, but it does indicate an electrical fault in a circuit that helps protect the transmission. If ignored under demanding driving conditions such as towing or performance driving, it can lead to transmission overheating and costly internal damage.

Q: How much does it cost to fix a P2799 code?

Repair costs vary widely depending on the root cause. Replacing a fuse or relay may cost only a few dollars. Repairing a wiring harness section typically ranges from $100 to $400 at a shop depending on labor time. Replacing an auxiliary transmission fluid pump can range from $200 to $600 or more depending on your vehicle make and model. Always get a diagnosis before authorizing major parts replacements.

Q: Will a P2799 code clear itself?

In some cases, if the fault was intermittent, the code may move to a pending status if it does not recur over a set number of drive cycles, and some vehicles will eventually clear it automatically. However, you should not rely on this. The underlying electrical issue needs to be found and fixed to prevent transmission damage. Use an OBD2 scanner to clear the code only after you have confirmed the repair.

Abstract

Error code P2799 means your vehicle's powertrain control module (PCM) has detected an abnormally high voltage signal in the auxiliary transmission fluid pump control circuit. This pump is responsible for keeping transmission fluid circulating and at the correct temperature, especially during towing, performance driving, or when the main pump alone isn't enough. Left unaddressed, this fault can lead to overheating, poor shifting, or long-term transmission damage.