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 |
|---|---|---|
| Engine coolant temperature [ECT Sensor 1] | 155.9°F (68.8°C) | - |
| Intake air temperature [IAT Sensor (1)] | 19°F (-7°C) | - |
| Engine speed [Engine Speed] | - | 3,000 rpm |
| MAP value [MAP Sensor] | - | 74 kPa (560 mmHg, 22.0 inHg) |
| 12 volt battery voltage [Battery] | 10.5 V | - |
| Fuel feedback | Closed loop | |
| Other | During fuel cut-off | |
[ ]: HDS Parameter
Malfunction Threshold
The estimated volume of intake air is 140 L/min (148 US qt/min, 124 lmp qt/min) - 170 L/min (180 US qt/min, 150 lmp qt/min) or more*.
*: Depends on engine speed and load
Possible Cause
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
- Start the engine. Hold the engine speed [Engine Speed] at 3,000 rpm without load (in P or N) until the radiator fan comes on.
- Drive the vehicle so that the vehicle enters the condition to perform fuel cut-off for at least 20 seconds.
- If the fuel cut-off condition did not continue for 20 seconds at once, repeat step 2.
- Drive the vehicle in this manner only if the traffic regulations and ambient conditions allow.
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, the freeze data, and the on-board snapshot 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, the freeze data, and the on-board snapshot can be cleared with the scan tool clear command.