Cracked or torn intake air duct between the mass airflow sensor and throttle body; Loose or improperly seated air duct clamp at the throttle body or air box; Disconnected or damaged vacuum hose connected to the intake duct; Failed mass airflow sensor providing an inaccurate reading; Leaking intake manifold gasket or throttle body gasket; Cracked intake manifold or damaged PCV hose causing unmetered air entry; Missing or improperly installed oil filler cap or dipstick, allowing unmetered air into the crankcase

DTC codes / Chrysler codes / P1191

P1191 · ChryslerIntake Air Duct Air Leak

Q: What does code P1191 mean?

Intake Air Duct Air Leak. P1191 on Chrysler vehicles indicates that the engine computer has detected an intake air duct air leak, meaning unmetered air is entering the intake system downstream of the mass airflow sensor. The computer typically recognizes this condition when fuel trim values exceed a calibrated threshold, signaling that the engine is receiving more air than the sensor has measured.

P1191 on Chrysler vehicles indicates that the engine computer has detected an intake air duct air leak, meaning unmetered air is entering the intake system downstream of the mass airflow sensor. The computer typically recognizes this condition when fuel trim values exceed a calibrated threshold, signaling that the engine is receiving more air than the sensor has measured.

SystemPowertrain

Code typeChrysler specific

SeverityMedium

Fix difficultyIntermediate

AreaFuel and air metering

Symptoms you may notice

Illuminated check engine light, often with no other noticeable symptoms
Rough or erratic idle, sometimes fluctuating up and down
Hesitation or stumble during acceleration
Lean misfire codes or a pending misfire code stored alongside P1191
Whistling or hissing sound from the engine bay while running
Poor fuel economy or increased fuel smell at idle

Common causes, most likely first

Cracked or torn intake air duct between the mass airflow sensor and throttle body
Loose or improperly seated air duct clamp at the throttle body or air box
Disconnected or damaged vacuum hose connected to the intake duct
Failed mass airflow sensor providing an inaccurate reading
Leaking intake manifold gasket or throttle body gasket
Cracked intake manifold or damaged PCV hose causing unmetered air entry
Missing or improperly installed oil filler cap or dipstick, allowing unmetered air into the crankcase

How to diagnose and fix it

Inspect the entire intake air duct from the air box to the throttle body for cracks, tears, or loose clamps
Check all vacuum hoses and PCV hoses connected to the intake duct for proper connection and condition
Verify the oil filler cap and dipstick are fully seated and sealing correctly
Use a scan tool to monitor fuel trim values and confirm the lean condition before and after repairs
Perform a smoke test on the intake system to pinpoint any hidden leaks
Clean or replace the mass airflow sensor if contamination or failure is suspected
Clear the code and road test the vehicle to confirm the repair and ensure the code does not return

Hidden intake leaks that trigger P1191

A loose oil filler cap or dipstick can allow unmetered air into the crankcase and trigger P1191 on Chrysler engines, so always check these simple items first.
The intake air duct often cracks on the underside or at the flex joint where it is difficult to see, so a visual inspection must include squeezing and flexing the duct while the engine runs.
A dirty or failing mass airflow sensor can report less air than actually enters the engine, mimicking a duct leak and leading to unnecessary replacement of the duct.
P1191 can be set by a vacuum leak at the intake manifold gasket even when the duct itself is intact, so a smoke test is the definitive way to find the source.
After repairing the leak, the fuel trim values may take a few drive cycles to relearn, so do not assume the repair failed if the light stays on briefly.

Can I keep driving with P1191?

You can drive the vehicle short distances to a repair shop, but avoid heavy acceleration or towing until the leak is fixed. Prolonged driving with a lean condition can cause misfires and damage the catalytic converter.

Tools that help

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Guidance is general and written for Chrysler vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.