P279A
Transfer Case Gear High Incorrect Ratio
When the transfer case is in High range the measured input/output speed ratio does not match the expected value. Worn chain or planetary set.
- Check engine light: Yes
- Emissions related: No
- Repair difficulty: hard
Common causes
Ordered by how often each turns out to be the cause.
- Stretched transfer case chainCommon
- Worn planetary gear setPossible
Parts involved
- Transfer Case
- Planetary Gear Set
P279A is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.