What does code P0174 mean on a Subaru and is it safe to drive?
P0174: System Too Lean (Bank 2). Here's what it means on your Subaru, what usually causes it, what repairs typically cost, and how safe it is to keep driving.
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What this code means
Same as P0171 but for bank 2. The engine is running too lean on the side that contains cylinder 2.
Common causes for your Subaru
- Vacuum leaks affecting bank 2
- Faulty MAF or O2 sensor
- Fuel delivery issues
Symptoms
- Check Engine Light
- Rough idle, hesitation
- May appear with P0171 on V6/V8 engines
Typical fixes
- Smoke test for vacuum leaks
- Inspect intake gaskets and hoses
- Check fuel pressure and filter
Repair cost range
For a Subaru, repairs for P0174 often fall between $100 and $600, depending on the cause and whether you use OEM or aftermarket parts. Labor rates vary by location.
Known issues on Subaru
Subaru H6 P0174 is a Bank 2 lean code on the rear cylinder bank. Vacuum leaks at the rear bank's intake runners are harder to visually inspect. Use a smoke machine—a MAF sensor cleaning should be the first step before testing for vacuum leaks on this complex engine.
Most commonly affected models
Outback H6 EZ30 2001–2009Legacy H6 EZ36 2008–2012Tribeca H6 2006–2007