B0290 code meaning
Rear Defrost Switch Circuit
What B0290 means
B0290 has no public source: the publicly available J2012 tables omit it, and service literature is silent. The title names the push button that requests the heated rear window. On the 2011 Saab 9-5 (GM) that button sits in the climate control faceplate, which passes the request to the climate module; only the relay output has its own code there (B0283). Saab's 9-3 monitors the button lamp separately as B0969 02. Patents US4555743A and US4673797A describe the usual logic: a momentary switch starts a timer of about ten minutes and can cancel it again. A switch fault means requests are lost or seen all the time, so the rear window either never heats or restarts by itself.
B0290 at a glance
- Check engine lightUsually not
- Emissions testNot an emissions code
- Limp modeNot expected
- Repair difficultyEasy, DIY possible
- Typical labor0.3 to 1.5 hours
- Clears after repairWhen cleared with a scanner
Symptoms of B0290
- Pressing the rear defrost button has no effect
- Rear window heating switches on by itself or cannot be cancelled
- Indicator lamp in the button stays dark or lit
Common causes of B0290
- Most likelyRear defrost button contacts worn or button stuck in the panel
- PossibleClimate control faceplate or its circuit board defective
- Less likelySignal or data line between panel and module interrupted
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Rear defrost switchBody control module
What each part of B0290 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). |
| 90 | The exact fault in that area. |
What to do next
- Note B0290 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 B0290
What does B0290 mean?
B0290 means "Rear Defrost Switch Circuit". B0290 has no public source: the publicly available J2012 tables omit it, and service literature is silent. It is a generic code, so it means the same on every make.
Is it safe to drive with B0290?
B0290 does not normally turn on the check engine light by itself. Watch for the symptoms above and have it checked soon.
Will B0290 fail an emissions test?
B0290 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 B0290 to fix?
Difficulty: easy. A typical repair takes 0.3 to 1.5 hours of work. A careful DIY repair is possible with basic tools and a scanner.
Will B0290 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.