Severity: Fix within days. Drive with caution and watch for new symptoms.
On Ford vehicles, this means the upstream oxygen sensor on bank 1 is not switching between rich and lean the way it should, and the engine is running lean.
Check for vacuum leaks, clean the MAF sensor, and test the oxygen sensor and fuel pressure.
Hesitation and rough idle are common. Get it checked soon.
You can drive short distances carefully; watch for worsening symptoms. Hesitation and rough idle are common. Get it checked soon.
The most common causes are: Vacuum leak; Dirty mass air flow sensor; Failing oxygen sensor; Low fuel pressure; Exhaust leak. A scan tool and a visual check of the parts above is where a technician starts.
Check for vacuum leaks, clean the MAF sensor, and test the oxygen sensor and fuel pressure.
