Toyota Tundra. Manual — part 1423

Fig. 225: Evaporative Emission System Operation Diagram

P2420: Vent valve stuck open (vent)

In operation C, the vent valve turns ON (closes) and the EVAP system pressure is then measured by the ECM
using the canister pressure sensor to conduct an EVAP leak check. If the pressure does not increase when the
vent valve is open, the ECM interprets this as the vent valve being stuck open. The ECM illuminates the MIL
and sets the DTC.

2008 Toyota Tundra

2008 ENGINE PERFORMANCE Engine Control System (2UZ-FE) - Tundra

Fig. 226: EVAP Pressure Graph - Vent Valve Stuck Open (Vent)

MONITOR STRATEGY

MONITOR STRATEGY

TYPICAL ENABLING CONDITIONS

TYPICAL ENABLING CONDITIONS

Required Sensors/Components

Purge VSV and canister pump module

Frequency of Operation

Once per driving cycle

Duration

Within 2 minutes (varies with amount of fuel in tank)

MIL Operation

2 driving cycles

Sequence of Operation

None

Monitor runs whenever following DTCs not present

None

EVAP key-off monitor runs when all of following conditions met -
Atmospheric pressure

70 to 110 kPa-a (525 to 825 mmHg-a)

Battery voltage

10.5 V or higher

Vehicle speed

Below 4 km/h (2.5 mph)

Ignition switch

Off

Time after key off

5 or 7 or 9.5 hours

Canister pressure sensor malfunction (P0451, P0452 and P0453)

Not detected

Purge VSV

Not operated by scan tool

Vent valve

Not operated by scan tool

2008 Toyota Tundra

2008 ENGINE PERFORMANCE Engine Control System (2UZ-FE) - Tundra

TYPICAL MALFUNCTION THRESHOLDS

TYPICAL MALFUNCTION THRESHOLDS

MONITOR RESULT

Refer to CHECKING MONITOR STATUS .

DTC P2431 SECONDARY AIR INJECTION SYSTEM AIR FLOW/PRESSURE SENSOR CIRCUIT
RANGE/PERFORMANCE BANK 1; DTC P2432 SECONDARY AIR INJECTION SYSTEM AIR
FLOW/PRESSURE SENSOR CIRCUIT LOW BANK 1; DTC P2433 SECONDARY AIR INJECTION
SYSTEM AIR FLOW/PRESSURE SENSOR CIRCUIT HIGH BANK 1; DTC P2436 SECONDARY AIR
INJECTION SYSTEM AIR FLOW/PRESSURE SENSOR CIRCUIT RANGE/PERFORMANCE BANK
2; DTC P2437 SECONDARY AIR INJECTION SYSTEM AIR FLOW/PRESSURE SENSOR CIRCUIT
LOW BANK 2; DTC P2438 SECONDARY AIR INJECTION SYSTEM AIR FLOW/PRESSURE
SENSOR CIRCUIT HIGH BANK 2

DESCRIPTION

The Secondary Air injection (AIR) system consists of an air pump, the Air Switching Valve (ASV), a pressure
sensor, the Air Injection Control Driver (AID) and the ECM. For a short time after cold engine starts, the AIR
system pumps secondary air to the exhaust port of the cylinder head to purify the exhaust emissions. The
secondary air is supplied by the air pump and is pumped to the exhaust port through the ASV.

The AID drives the ASV and the air pump according to command signals transmitted by the ECM. The pressure
sensor detects the pressure in the secondary air passage when the AIR system is ON and OFF, and transmits a
pressure signal to the ECM.

The AID is not only equipped to drive the pump and valve, but also with a diagnosis function to detect
malfunctions in the AIR system circuit.

HINT:

As a large current is required to drive the air pump and ASV, an AID is installed to this system.

Leak detection pump

Not operated by scan tool

Both of following conditions met before key off

Conditions 1 and 2

1. Duration that vehicle driven

5 minutes or more

2. EVAP purge operation

Performed

ECT

4.4 to 35°C (40 to 95°F)

IAT

4.4 to 35°C (40 to 95°F)

EVAP pressure change after EVAP canister vent valve ON

Less than 0.3 kPa-g (2.25 mmHg-g)

2008 Toyota Tundra

2008 ENGINE PERFORMANCE Engine Control System (2UZ-FE) - Tundra

Fig. 227: Air Injection System Air Flow Diagram

DTC DETECTION CONDITION AND TROUBLE AREA

MONITOR DESCRIPTION

DTC

Code

DTC Detection Condition

Trouble Area

P2431
P2436

Pressure sensor indicates less than 45.6 kPa (342 mmHg), or
more than 135 kPa (1013 mmHg) (2 trip detection logic)



Pressure sensor



Open or short in
pressure sensor circuit



ECM

P2432
P2437

While engine running, voltage output of pressure sensor remains
below 0.5 V (1 trip detection logic)



Pressure sensor



Open or short in
pressure sensor circuit



ECM

P2433
P2438

While engine running, voltage output of pressure sensor remains
above 4.5 V (1 trip detection logic)



Pressure sensor



Open or short in
pressure sensor circuit



ECM

2008 Toyota Tundra

2008 ENGINE PERFORMANCE Engine Control System (2UZ-FE) - Tundra