The Service Manual says the most likely cause of P2173 is a vacuum leak.
A large vacuum leak is most likely the cause of this DTC.
Inspect the Intake Manifold and Throttle body for leaks and cracks.
Inspect the Power Brake Booster for any vacuum leaks.
Inspect the PCV system for proper operation or any vacuum leaks.
Inspect the MAP Sensor for proper installation.
P2173-HIGH AIRFLOW/VACUUM LEAK DETECTED (SLOW ACCUMULATION) (CONTINUED)
² When Monitored:
Ignition on and engine running with no MAP Sensor DTCs.
² Set Condition:
A large vacuum leak has been detected or both of the TP Sensors have failed based on their position being
2.5 volts and the calculated MAP value is less than the Gas Flow Adaptation value is too high. One trip fault the code will set within 5 seconds. ETC light will flash.
Possible Causes
VACUUM LEAK
RESISTANCE IN THE (F856) 5-VOLT SUPPLY CIRCUIT
(F856) 5-VOLT SUPPLY CIRCUIT SHORTED TO GROUND
RESISTANCE IN THE (K1) MAP SIGNAL CIRCUIT
(K1) MAP SIGNAL CIRCUIT SHORTED TO GROUND
RESISTANCE IN (K900) SENSOR GROUND CIRCUIT
RESISTANCE IN THE (F855) 5-VOLT SUPPLY CIRCUIT
(F855) 5-VOLT SUPPLY CIRCUIT SHORTED TO GROUND
RESISTANCE IN THE TP SENSOR SIGNAL CIRCUIT
TP SENSOR SIGNAL CIRCUIT SHORTED TO GROUND
RESISTANCE IN THE (K922) TP SENSOR RETURN CIRCUIT
MAP SENSOR
TP SENSOR
PCM
