Table 7

WARNING: This page is about a different car, the 2010 Mercury Mariner and 2010 Ford Escape. However, it is still accessible from the selected car via links, so may be relevant.

Poor Fuel Economy

NOTE: Since driving styles can have a significant influence on fuel economy, verify the concern before starting an in-depth diagnosis.

NOTE: Excessive temperatures in the high voltage traction battery will cause the engine to run longer than normal to cool the high voltage traction battery and will result in reduced fuel economy. The high voltage traction battery cooling system should be checked for proper operation if there is no obvious cause for the additional cooling request. The following external factors may also contribute to poor fuel economy conditions:

stop/go driving
incorrect tire pressure/size
vehicle loads (such as trailer towing)
extended winter warm-up conditions
high speed driving
regenerative braking disabled
high voltage traction battery temperatures

incorrect axle ratio
road/weather conditions
aftermarket add-ons
short run operations
customer expectations

POOR FUEL ECONOMY SYMPTOM TABLE

SYSTEM/COMPONENT	REFERENCE (Pinpoint Test unless noted)
Transaxle Fluid Level	Visual. REFER to AUTOMATIC TRANSAXLE/TRANSMISSION - 6F35 -- FUSION & MILAN , AUTOMATIC TRANSAXLE/TRANSMISSION - AISIN AW21 or AUTOMATIC TRANSAXLE/TRANSMISSION - ELECTRONICALLY CONTROLLED CONTINUOUSLY VARIABLE TRANSMISSION (ECVT) .
Check the following PIDs: LONGFT1 (value between -20 and +20) VPWR (value between 10.5 and 17.0 volts, and within 0.5 volt of battery voltage)	LONGFT1 value low (-): Continue diagnosis. Concentrate checks in areas that cause the engine to run rich. LONGFT1 value high (+): Continue diagnosis. Concentrate checks in areas that cause the engine to run lean. VPWR not between 10.5 and 17.0 volts: REFER to CHARGING SYSTEM . VPWR between 10.5 and 17.0 volts, but not within 0.5 of battery voltage: CHECK the B+ supply to the power relay. CHECK the VPWR circuit between the PCM and the power relay. CHECK the PWR GND circuits.
Verify the engine operates at normal temperature.	Visual. REFER to ENGINE COOLING - HYBRID , to diagnose any cooling system concerns that are present.
Secondary Ignition System	GO to PINPOINT TEST JB .
Fuel System	GO to PINPOINT TEST HC .
Exhaust System	GO to PINPOINT TEST HF .
Variable Camshaft Timing (VCT) System	GO to PINPOINT TEST HK .
Automatic Transaxle	REFER to AUTOMATIC TRANSAXLE/TRANSMISSION - 6F35 -- FUSION & MILAN , AUTOMATIC TRANSAXLE/TRANSMISSION - AISIN AW21 or AUTOMATIC TRANSAXLE/TRANSMISSION - ELECTRONICALLY CONTROLLED CONTINUOUSLY VARIABLE TRANSMISSION (ECVT) .
PCV System	GO to PINPOINT TEST HG .
Additional Checks: Correct PCM vehicle identification (VID) block information. Refer to FLASH ELECTRICALLY ERASABLE PROGRAMMABLE READ ONLY MEMORY (EEPROM) . Brake drag Base engine concerns Incorrect PCV valve Contaminated MAF sensor Intake air system	REFER to the applicable article in the Workshop Manual.
Additional Testing	GO to PINPOINT TEST Z .