P1609

DTC Code	DTC Name
P1609	Air Fuel Ratio Too Rich

DESCRIPTION

This DTC is stored if the ECM detects that the air fuel ratio is too rich due to a malfunction in the fuel system, mass air flow meter or diesel turbo pressure sensor.

Using the intelligent tester, the conditions present when the DTC was stored can be confirmed by referring to the freeze frame data. Freeze frame data records engine conditions when a malfunction occurs. This information can be useful when troubleshooting.

Table 1. P1609
DTC Detection Drive Pattern	DTC Detection Condition	Trouble Area
-	Both of the following conditions 1 and 2 are met for approximately 2 seconds: (1 trip detection logic) All of the following conditions are met: Engine not being started Air fuel ratio sensor is active (warmed up) Mass air flow meter is normal Diesel turbo pressure sensor is normal Air fuel ratio sensor output value exceeds the threshold	Intake system clogged Electric EGR control valve assembly stuck closed Deterioration of mass air flow meter (out of range) Intake system hose disconnected or cracked Turbocharger sub-assembly vane stuck fully open Diesel turbo pressure sensor Atmospheric pressure sensor (built into ECM) Suction control valve (built into supply pump assembly) sticking Fuel leak Fuel pressure sensor (built into common rail assembly) Engine coolant leak Radiator assembly clogged Engine coolant temperature sensor Engine coolant temperature sensor out of range or stuck

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CAUTION / NOTICE / HINT

In contrast to normal malfunction diagnosis for components, circuits and systems, DTC P1609 is used to determine the malfunctioning area from the problem symptoms and freeze frame data when the user mentions problems such as black smoke or white smoke emitted.

As the DTC can be stored as a result of certain user actions, even if the DTC is output, if the customer makes no mention of problems, clear the DTC without performing any troubleshooting and return the vehicle to the customer.
If any other DTCs are output, perform troubleshooting for those DTCs first.
Read freeze frame data using the intelligent tester. Freeze frame data records the engine condition when malfunctions are detected. When troubleshooting, freeze frame data can help determine if the vehicle was moving or stationary, if the engine was warmed up or not, and other data from the time the malfunction occurred.
When confirming the freeze frame data, be sure to check all 5 sets of freeze frame data.

Table 2.
*a	DTC is stored
*b	0.5 seconds
*c	Freeze frame data recorded point

The fourth set of freeze frame data is the data recorded when the DTC is stored.

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PROCEDURE

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READ OUTPUT DTC (RECORD STORED DTC AND FREEZE FRAME DATA)
1. Connect the intelligent tester to the DLC3.
2. Turn the ignition switch to ON and turn the tester on.
3. Enter the following menus: Powertrain / Engine and ECT / DTC.
4. Record the stored DTC and Freeze Frame Data.
  
  Tip:
  This freeze frame data shows the actual engine conditions when air fuel ratio too rich trouble occurred.
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CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO DTC P1609)

Connect the intelligent tester to the DLC3.
Turn the ignition switch to ON and turn the tester on.
Enter the following menus: Powertrain / Engine and ECT / DTC.

Read the DTCs.

Table 3. Result
Result	Proceed to
DTC P1609	A
DTC P1609 and other DTCs	B

Tip:

If any DTCs other than DTC P1609 are output, troubleshoot those DTCs first.

A
GO TO BLACK SMOKE EMITTED (Click here)
B
GO TO DTC CHART (Click here)

ECD SYSTEM(w/o DPF), Diagnostic DTC:P1609