Acura RL. Instruction — page 27

Conditions for illuminating the MIL

When a malfunction is detected during the first drive cycle with the ECT and IAT at engine start-up within
the specified temperature range, a Temporary DTC is stored in the PCM memory. If the malfunction recurs
during the next (second) drive cycle with the ECT and IAT at engine start-up within the specified
temperature range, the MIL comes on and the DTC and the freeze frame data are stored.

Conditions for clearing the MIL

The MIL will be cleared if the malfunction does not recur during three consecutive trips in which the
diagnostic runs.

The MIL, the DTC, the Temporary DTC, and the freeze frame data can be cleared by using the scan tool
Clear command or by disconnecting the battery.

DTC P0456 (90): ADVANCED DIAGNOSTICS

DTC P0456: EVAPORATIVE EMISSION (EVAP) SYSTEM VERY SMALL LEAK DETECTED

Fig. 79: Evaporative Emission System Diagram

2007 Acura RL

2007 ENGINE PERFORMANCE Advanced Diagnostics — RL

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Fig. 80: Evaporative Emission System Diagnosis Execution

General Description

The evaporative emission (EVAP) leak detection system uses a vacuum-retention (decompression) method
and an engine off natural vacuum (EONV) method. This method detects leakage by monitoring the vacuum-
retention ability of the EVAP system (from EVAP canister purge valve to fuel tank). The EONV method
detects leakage from the change in fuel tank pressure via the fuel tank pressure (FTP) sensor with the engine
off.

Here is an overview of the malfunction detection for the EONV method:

Step 0: Judgement of detection of 0.09 inch leak as normal operation < decompressing monitor >

Step 1: Judgement of detection of 0.02 inch leak as normal operation < phase 1 >

Step 2: Detection of 0.02 inch leak < phase 2 >

Step 0:

Once required conditions for the monitor are met, the powertrain control module (PCM) applies vacuum to
the EVAP system line from the purge control solenoid (PCS) valve through the fuel tank, and monitors the
variation of the FTP sensor output to detect a «0.09 inch leak».

If a «0.09 inch leak» is detected, it is identified as a malfunction; the diagnosis is complete.

If «no 0.09 inch leak» is detected, the PCM goes to step 1, judgement of detection of a 0.02 inch leak
as normal operation < phase 1 >.

If sufficient vacuum cannot be drawn on the EVAP system line, it is identified as either «EVAP
system low purge flow (P0497)» or «EVAP system leak detected fuel fill cap loose/off (P0457)» (refer
to the applicable DTC detail).

Step 1:

After the engine has stopped, the PCM monitors the variation of the FTP sensor output to detect «no 0.02

2007 Acura RL

2007 ENGINE PERFORMANCE Advanced Diagnostics — RL

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Page 106 © 2005 Mitchell Repair Information Company, LLC.

inch leak» depending on the variation corresponding to the increasing pressure inside the fuel tank.

If «no 0.02 inch leak» is detected, it is identified as normal; the diagnosis is complete.

If «no 0.02 inch leak» is not detected, the PCM goes to step 2, detection of a 0.02 inch leak < phase 2
>.

Step 2:

The PCM continues to monitor the FTP sensor output to detect «no 0.02 inch leak» depending on the
variation corresponding to the decreasing pressure inside the fuel tank.

If a «0.02 inch leak» is detected, it is identified as a malfunction; the diagnosis is complete.

If «no leakage» is detected, it is identified as normal; the diagnosis is complete.

Monitor Execution, Sequence, Duration, DTC Type, OBD Status

MONITOR DESCRIPTION CHART

Enable Conditions

ENABLE CONDITIONS

Execution

Once per driving cycle

Sequence

P0455, P0457, P0497 are judged as OK

Duration

At least 11 minutes, 37 seconds but not more than 31 minutes, 37 seconds

DTC Type

Two drive cycles, MIL ON

OBD Status

N/A

Condition

Minimum

Maximum

Elapsed time before starting the
engine

6 hours

Initial condition A

(1)

18°F (10°C)

Initial condition B

(2)

18°F (10°C)

Initial engine coolant temperature 40°F (5 °C)

95°F (35°C)

Initial intake air temperature

40°F (5 °C)

95°F (35°C)

Barometric pressure

76 kPa (22.5 in.Hg, 569 mmHg) —

Battery voltage

10.5 V

No active DTCs

P0111, P0112, P0113, P0116, P0117, P0118, P0125, P0443,
P0451, P0452, P0453, P0455, P0457, P0496, P0497, P0498,
P0499, P0685, P1109, P1116, P1454, P2227, P2228, P2229,
P2422, P2610

Others

Other than when there is excessive vapor generation (fuel level is
not full)
Avoid abrupt acceleration, deceleration, and turns
Test-drive on a flat road to avoid misdetection
Drive for 1 hour or more
No refueling is required

(1)

The initial intake air temperature minus the current intake air temperature

2007 Acura RL

2007 ENGINE PERFORMANCE Advanced Diagnostics — RL

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Page 107 © 2005 Mitchell Repair Information Company, LLC.

Malfunction Threshold

The variation of pressure inside the fuel tank after phase 1 is 0.3 kPa (0.1 in.Hg, 2.8 mmHg) or more
(depending on fuel level and barometric pressure).

The sum of the variations of pressure inside the fuel tank after phase 1 and phase 2 is 10 kPa (3.1 in.Hg, 80
mmHg) or less (depending on fuel level and barometric pressure).

The barometric pressure is stable for at least 20 minutes.

Confirmation Procedure with the HDS

Do the EVAP FUNCTION TEST in the INSPECTION MENU with the HDS.

Driving Pattern

1. After the vehicle has been left for an appropriate amount of time as specified, with the engine coolant

temperature and intake air temperature within the specified range, start the engine.

2. Warm up the engine at idle until the radiator fan comes on.

3. Drive the vehicle immediately at a speed between 45 — 75 mph (72 — 120 km/h) for at least 20 minutes.

4. After stopping the engine, turn the ignition switch off, and leave the vehicle for 32 minutes or more

(EONV executes).

Drive the vehicle in this manner only if the traffic regulations and ambient conditions allow.

Diagnosis Details

Conditions for illuminating the MIL

When a malfunction is detected during the first drive cycle with the ECT and IAT at engine start-up within
the specified temperature range, a Temporary DTC is stored in the PCM memory. If the malfunction recurs
during the next (second) drive cycle with the ECT and IAT at engine start-up within the specified
temperature range, the MIL comes on and the DTC and the freeze frame data are stored.

Conditions for clearing the MIL

The MIL will be cleared if the malfunction does not recur during three consecutive trips in which the
diagnostic runs.

The MIL, the DTC, the Temporary DTC, and the freeze frame data can be cleared by using the scan tool
Clear command or by disconnecting the battery.

DTC P0457 (90): ADVANCED DIAGNOSTICS

DTC P0457: EVAPORATIVE EMISSION (EVAP) SYSTEM LEAK DETECTED/FUEL FILL CAP
LOOSE OR MISSING

(2)

The initial engine coolant temperature minus the initial intake air temperature

2007 Acura RL

2007 ENGINE PERFORMANCE Advanced Diagnostics — RL

me

Friday, June 05, 2009 2:32:04 PM

Page 108 © 2005 Mitchell Repair Information Company, LLC.

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