B0339 code meaning
Rear Seat Heater Circuit
What B0339 means
B0339 shows up neither in the public code lists nor in published service material. Rear seat heating is an option on larger cars; the GM-built 2011 Saab 9-4X with heated rear seats has a dedicated control module behind the rear backrest. It feeds both mats through a common supply, regulates by switching their ground with PWM and checks current and voltage every 10 s: B2425/B2430 0D mean element resistance too high, 0B/0E too much current or too little resistance. Each rear seat also carries an NTC sensor (B1925/B2170), and B2345 13 reports the shared disable line. US5229579A shows why such controllers shut off on a short or an open circuit.
B0339 at a glance
- Check engine lightUsually not
- Emissions testNot an emissions code
- Limp modeNot expected
- Repair difficultyMedium
- Typical labor0.5 to 4 hours
- Clears after repairWhen cleared with a scanner
Symptoms of B0339
- One or both rear seat heaters stay cold
- Rear seat heating indicator flashes or goes out
Common causes of B0339
- Most likelyHeating mat in a rear seat cushion broken
- PossibleConnector damaged when the rear seat was folded or removed
- PossibleRear seat heating control module or its supply faulty
- Less likelySeat temperature sensor implausible so heating is disabled
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Seat heater elementRear seat wiring
What each part of B0339 means
| B | Body system: airbags, seat belts, power seats, lights and climate control. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 39 | The exact fault in that area. |
What to do next
- Note B0339 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about B0339
What does B0339 mean?
B0339 means "Rear Seat Heater Circuit". B0339 shows up neither in the public code lists nor in published service material. It is a generic code, so it means the same on every make.
Is it safe to drive with B0339?
B0339 does not normally turn on the check engine light by itself. Watch for the symptoms above and have it checked soon.
Will B0339 fail an emissions test?
B0339 is not an emissions code, so on its own it usually does not fail an emissions test. Other stored codes or a lit check engine light still can.
How hard is B0339 to fix?
Difficulty: medium. A typical repair takes 0.5 to 4 hours of work. This is a job for a workshop.
Will B0339 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.