DTC Advanced Diagnostics: P2279
DTC P2279:Intake Air System Leak

General Description


The positive crankcase ventilation (PCV) system reduces hydrocarbon (HC) emissions. The PCV system recirculates unburned air/fuel mixture (blow-by gas) into the intake manifold so that it is drawn into the engine and burned, thus reducing HC. If the PCV hose comes off at idle with the throttle closed, the amount of air supplied to the engine is considerably more than the amount of air the idle control system supplies. The powertrain control module (PCM) estimates the amount of air supplied to the engine while the throttle valve is fully closed, and if the estimated amount is more than the upper limit, it detects a malfunction and stores a DTC.

Monitor Execution, Sequence, Duration, DTC Type
Execution
Once per driving cycle
Sequence
None
Duration
22 seconds or more
DTC Type
Two drive cycles, MIL on

Enable Conditions
Condition
Minimum
Maximum
Elapsed time after VTEC switched
3.0 seconds
–
Elapsed time after starting the engine
15 seconds
–
Engine coolant temperature [ECT SENSOR 1]
156 °F (69 °C)
–
Intake air temperature
[IAT Sensor (1)]
19 °F (-7 °C)
–
MAP value [MAP SENSOR]
–
87 kPa (655 mmHg, 25.7 inHg)
12 volt battery voltage
[BATTERY]
10.5 V
–
Fuel trim
0.69
1.47
Fuel feedback
Closed loop
Other
At idle
[ ]: HDS Parameter

Malfunction Threshold
Either of these conditions is met:
The estimated volume of intake air is 200 L/min (211.4 US qt/min, 176 lmp qt/min) or more when the MAP value [MAP SENSOR] is 35 kPa (260 mmHg, 10.3 inHg).
The estimated volume of intake air is 160 L/min (169.1 US qt/min, 140.8 lmp qt/min) or more when the MAP value [MAP SENSOR] is 48 kPa (360 mmHg, 14.2 inHg).

Possible Cause
NOTE: The causes shown may not be a complete list of all potential problems, and it is possible that there may be other causes.
Vacuum hose misinstalled
Throttle body air leak
Intake manifold air leak
Evaporative emission (EVAP) canister purge valve failure
Valve timing incorrect
Manifold absolute pressure (MAP) sensor range/performance problem

Confirmation Procedure
Operating Condition
1.
Start the engine. Hold the engine speed [ENGINE SPEED] at 3,000 rpm without load (CVT in P or N, M/T in neutral) until the radiator fan comes on.
2.
Let the engine idle for at least 22 seconds.
With the HDS
None.

Diagnosis Details
Conditions for setting the DTC
When a malfunction is detected during the first drive cycle, a Pending DTC is stored in the PCM memory. If the malfunction returns in the next (second) drive cycle, the MIL comes on and a Confirmed DTC and the freeze data are stored.

Conditions for clearing the DTC
The MIL is cleared if the malfunction does not return in three consecutive trips in which the diagnostic runs. The MIL, the Pending DTC, the Confirmed DTC, and the freeze data can be cleared with the scan tool Clear command or by disconnecting the 12 volt battery.