DTC P1191 Intake Air Duct Leak. GMC Truck GMC K Pickup

For 1990-2009 cars only

Makes 🢒 GMC_Truck 🢒 1997 🢒 GMC K Pickup - 4WD 🢒 Engine 🢒 Engine Controls - 6.5L 🢒 DTC P1191 Intake Air Duct Leak

Engine Controls Components
DIESEL PCM, MAF, EGR, APP, WASTEGATE
OBD II Symbol Description Notice
Handling ESD Sensitive Parts Notice

Circuit Description

The Mass Air Flow (MAF) sensor measures the amount of air entering the engine during a given time. The PCM uses the mass air flow information to monitor EGR flow rates. A large quantity of air entering the engine indicates an acceleration or high load situation, while a small quantity of air indicates deceleration or idle.

The PCM has the ability to determine a intake leak by using the Mass Air Flow (MAF) sensor and the EGR Control Pressure / BARO sensor.

Conditions for Setting the DTC

•	DTCs P0405, P0406, P0102 and P0103 are not set.

•	All EGR tests have been completed (internal to PCM).

•	Intake leak greater than calibarteted value (internal to PCM)

Action Taken When the DTC Sets

The MIL will illuminated on the second test fail.

Conditions for Clearing the MIL/DTC

•	The PCM will turn the MIL off after three consecutive trips without a fault condition.

•	A History DTC will clear when forty consecutive warm-up cycles that the diagnostic does not fail (coolant temperature has risen 5°C (40°F) from start up coolant temperature and engine coolant temperature exceeds 71°C (160°F) that same ignition cycle.

•	Use of a Scan tool

Diagnostic Aids

The most likely cause of failure is a leaky intake duct after the MAF sensor.

To run the diagnostic test the engine must be at operating temperature, vehicle in drive at idle for approximately 1 minute, then with vehicle in park hold engine rpm steady between 1500 and 2100 rpm for 30 seconds. If the diagnostic test fails to run, vehicle must be driven.

Test Description

Number(s) below refer to the step number(s) on the Diagnostic Table.

A large leak in the intake system will set MAF sensor DTC. All intake ducts should be checked after the MAF sensor.

Step

Action

Value(s)

Yes

Important: Before clearing DTC(s) use the scan tool Capture Info to record freeze frame and failure records for reference, as data will be lost when Clear Info function is used.

Was the Powertrain On-Board Diagnostic (OBD) System Check performed?

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

Are there any EGR DTCs set?

Go to the applicable DTC Table

Go to Step 3

Check for the following conditions:

•	Air inlet duct leaks (after the MAF sensor).

•	Missing EGR tower gasket

•	All intake manifold gaskets in place.

Has a repair been performed?

Go to Step 4

Important: After repairs, the EGR ALM cells must be reset (under special functions in scan tool).

Are EGR ALM cells reset?

Go to Step 5

Using the Scan Tool, select DTC, Clear Info.
Start the engine and idle at normal operating temperature.
Select DTC, Specific, then enter the DTC number which was set.
Operate the vehicle until the Scan Tool indicates that the diagnostic Ran.

Does the Scan Tool indicate that this diagnostic Passed?

Go to Step 6

Go to Step 2

Using the Scan Tool, select Capture Info, Review Info.

Are any DTCs displayed that have not been diagnosed?

Go to the Applicable DTC Table

System OK