P0170 — Fuel Trim Malfunction (Bank 1)
CAUTIONIs it safe to drive? Drive gently and get it looked at soon — it can worsen or fail inspection.
What P0170 means
This is a manufacturer-specific code — its meaning depends on the vehicle’s make (see below).
What P0170 means on specific makes
Mercedes-Benz CAUTION
Generic code, common on Mercedes. Fuel trims on bank 1 have drifted beyond range (either direction) — on MB frequently a vacuum/intake leak, a clogged fuel filter, or cam-adjuster oil leaking into the O2 sensor harness.
- Vacuum leak: intake manifold, valve cover, breather cover ($20-200)
- Clogged fuel filter (cheap, real-world fix on older MB) ($30-80)
- Cam actuator oil leaking into wiring harness
- MAF sensor drift ($150-350)
Check first: Check fuel trims and smoke-test for leaks. On older MB a new fuel filter has resolved P0170 + P0410 combos. Inspect O2/cam harness for oil contamination.
Source: BenzWorld 'P0170 & P0410 solved with new fuel filter'; RepairPal P0170