P0171
Fix soonEngine & fuel systemSystem too lean (bank 1)
Bank 1 is running with too much air relative to fuel. Long-term fuel trim has hit the ECU's correction ceiling.
Common causes
- Vacuum leak (cracked hose, bad PCV, intake gasket)
- Failing fuel pump
- Dirty MAF sensor
- Leaking injector seal
First thing to try:
Smoke test the intake; replace the air filter; check for hissing under the hood at idle.
Can I keep driving?
Short trips only. Book a diagnosis soon — driving on this fault can damage other parts.
Who fixes P0171
This one falls under Fault code diagnosis. Verified specialists can read it live over a remote session, usually in a few minutes — you only pay if it works.
Full guide
P0171 Meaning: System Too Lean (Bank 1) ExplainedLearn what P0171 means, common causes, live scan PIDs, DIY checks, and when to consult a specialist.Related codes
These explanations are from a curated DTC knowledge base. Manufacturer-specific codes may need a specialist's hands-on read.