P1101 on Buick: How to Diagnose & Fix
Intake Airflow System Performance
1 Buick model · 1 documented issue · $150-$900 repair
On Buick vehicles, P1101 (intake airflow system performance) is most often reported on the 2013-2022 Buick Encore as 1.4L Turbo Intake Manifold PCV Check Valve Failure - P1101/P0171 Lean Codes and Repeat Valve-Cover Failures ($150-$900 repair). Pull the PCV hose at the intake manifold and look into the port: if the orange check valve is missing, the manifold is the root cause. Official repair is a new intake manifold (roughly $400-$700 installed) plus a new camshaft cover if the diaphragm has torn ($200-$350). Each section below gives the symptoms, how to confirm the cause, the fix, parts and sources for that model.
Common causes of P1101 (all vehicles)
- Dirty or failing mass airflow (MAF) sensor
- Unmetered air/vacuum leak (intake duct, hose, or gasket)
- Loose or cracked air intake tube/boot
- Dirty or clogged air filter
- Faulty PCV system or hose
- Throttle body issues or carbon buildup
- Faulty manifold absolute pressure (MAP) sensor
- Wiring/connector problems at the MAF sensor
P1101 on Buick by model: symptoms, diagnosis and fix
This is the upstream half of the 1.4L PCV story and is often missed. The intake manifold on the LUV/LUJ 1.4T contains a small, non-serviceable orange one-way check valve in the PCV port. Under boost that valve is meant to block pressure from reaching the crankcase; when it fails and is ingested by the engine, boost pressure enters the crankcase, the camshaft-cover diaphragm tears, and the engine develops a large vacuum leak. The result is P1101 (intake airflow system performance) with P0171 (system too lean), rough idle, high idle, stalling and long-term fuel trims in the +25% to +70% range. Owners who replace only the valve cover watch the new one fail within months because the missing manifold check valve was never addressed. A ScannerDanner forum diagnosis of a 2019 Encore documents exactly this: check valve gone from the manifold, 70% fuel trim, fixed by an external PCV kit.
Common Symptoms
- Check engine light with P1101 and/or P0171
- Rough or surging idle
- High long-term fuel trims (+25% or more)
- Stalling at idle
- Whistle at the valve cover after diaphragm tears
- Repeat valve-cover failure after replacement
How to Fix
Pull the PCV hose at the intake manifold and look into the port: if the orange check valve is missing, the manifold is the root cause. Official repair is a new intake manifold (roughly $400-$700 installed) plus a new camshaft cover if the diaphragm has torn ($200-$350). Many owners instead install an external PCV fix kit (CruzeKits or equivalent) that relocates the check valve into a serviceable inline fitting, which is cheaper and prevents the repeat failure. Clear codes and confirm fuel trims return to single digits.
Looking for P1101 on a different make?
View P1101 across all makes →Frequently asked questions
What does P1101 mean on a Buick?
P1101 stands for "Intake Airflow System Performance." This manufacturer-related code (common on GM engines) means the intake airflow system is not performing within expected limits. The computer cross-checks the mass airflow (MAF) sensor reading against other inputs like throttle position and manifold pressure, and the values don't agree, suggesting metered airflow is wrong or air is getting in unmeasured. It often appears alongside lean-condition codes. Symptoms can include rough idle, hesitation, reduced power, and a check engine light. On Buick it is documented across 1 model: Encore.
How do I diagnose P1101 on a Buick Encore?
Pull the PCV hose at the intake manifold and look into the port: if the orange check valve is missing, the manifold is the root cause. Official repair is a new intake manifold (roughly $400-$700 installed) plus a new camshaft cover if the diaphragm has torn ($200-$350). Many owners instead install an external PCV fix kit (CruzeKits or equivalent) that relocates the check valve into a serviceable inline fitting, which is cheaper and prevents the repeat failure. Published repair guidance and available estimates are in the Encore section on this page.
What causes P1101 on Buick vehicles?
Documented causes on Buick: 1.4L Turbo Intake Manifold PCV Check Valve Failure - P1101/P0171 Lean Codes and Repeat Valve-Cover Failures. Generic causes of P1101: Dirty or failing mass airflow (MAF) sensor, Unmetered air/vacuum leak (intake duct, hose, or gasket), Loose or cracked air intake tube/boot, Dirty or clogged air filter.
How much does it cost to fix P1101 on a Buick?
Published repair estimates on Buick range from $150 to $900 depending on the model and root cause. If an issue mentions a recall or campaign, check your VIN with the manufacturer or NHTSA and confirm eligibility and coverage with a dealer.
Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.