One of the most common diagnostic trouble codes (DTC) Chevrolet Cruze users get is the P1101. The trouble code is expected because of the unreliable nature of the PCV (Positive Crankcase Ventilation) system that Chevrolet uses for most of its vehicles. This code and a few more will still reoccur even after replacing the whole PCV system.
There is a lot of misinformation on how this system works. Therefore, I’m going to go through a basic but clear overview of how the system works. Below is an outline of how the gas flows in a Gen 1 Chevy Cruze 1.4L Turbo PCV system.
The PCV system was created to help with the engine’s ventilation to have better efficiency and fuel economy from the engine. When the motor runs, some of the exhaust gas comes through the piston rings since there is no perfect seal, but most of it goes out through the car’s tailpipe.
The gas that comes through the piston ring enters the crankcase. This creates a positive pressure which has to be evacuated. The crankcase hosts an oil separator in the valve cover. The oil separator absorbs the oil vapor from the gas and redirects it back to the engine. The rest of the gas is directed through a chamber in the valve cover into the cylinder head and then enters the intake manifold, as shown.
There is one check valve at the entry of the intake manifold. This check valve is opened under vacuum with a PCV pressure control diaphragm to allow the gas in. The PCV pressure control diaphragm regulates the amount of vacuum produced by the intake manifold when the engine is under vacuum conditions on the crankcase (the ideal vacuum is 11-18 inches of water.)
The PCV pressure control diaphragm is shown below. A lot of people refer to it as the PCV valve or the PCV vacuum regulator diaphragm.
The PCV pressure control diaphragm is prone to failure. In most cases, this is the part you will have to fix to get rid of the P1101 code and similar ones depending on the problem’s length and severity.
Once the gas passes the first check valve, it flows through a corrugated hose that leads it into the second check valve at the turbo inlet, exiting it into the turbo inlet.
The P1101 code is mostly attributed to your PCV system’s condition, cleanliness, connections and wiring, the shape of the diaphragm, and sometimes the throttle body’s cleanliness. Various car parts will eventually develop carbon build-up and house deposits over a long period of use. This dirt may sometimes lead to the occurrence of the P1101 code.
The P1101 Definition
Definition: Intake Air Flow System Performance
In some other vehicles, the P1101 code is stored when the PCM detects a problem with the Mass Air Flow Sensor System (MAF). The PCM usually detects the problem when it runs its self-diagnostic test called the Key-On Engine Running (KOER) test. The problem is registered if the MAF voltage is lower or greater than the one set by the manufacturer.
What The P1101 Chevy Cruze Trouble Code means
The P1101 Chevy Cruze code is stored when the PCM detects a problem with the Intake Air Flow System’s performance. The problem is registered if the Intake Air Flow System’s performance is lower or greater than the one set by the manufacturer.
When you see this code, the issue lies within the realm of the Intake Air Flow System. This includes the PCV system, intake manifold, check valves, connectors, wiring, and any element associated with airflow along its vicinity.
Other codes that may be related to the P1101 code in Chevrolet Cruze vehicles (depending on the length and severity of the problem) are:
1. P0171 – Fuel Trim System Lean
3. P0507 – Idle Air Control – RPM higher than expected
Some Of The Symptoms Associated With The P1101 Code Are:
1. Rough idling
Due to the increased idle speed (measured in RPM – Revolutions Per Minute) of the engine. Idle speed is the rotational speed an engine runs when it is idling (the vehicle isn’t moving, but the engine is still running.) This number will vary depending on the car. In Chevy Cruze vehicles, the number ranges from 600-800 rpm depending on the engine cylinders and transmission mode.
2. Reduction in fuel economy – this will be apparent with an increase in the liters per 100km you use. The lower the number of liters stated, the better the fuel economy.
3. Engine running roughly – you will probably notice this when you start experiencing some shaking and bouncing sensation in the car, followed by odd sounds and irregular RPM.
4. Smoke from the tailpipe – smoke out of the tailpipe is associated with several causes such as oil leakage and condensation. The smoke may appear white or blue.
5. Hissing noise in the engine bay – this will imply that there may be a leak in the engine bay (punctured hose/broken connections) or a ruptured PCV pressure control diaphragm.
Causes Of The P1101 Trouble Code In Chevy Cruze Vehicles:
1. Broken or blocked PCV system hose – The blocked hose may cause the oil to be pushed up into the combustion chamber, causing the oil to burn inside the engine and out the exhaust pipe.
2. Check valves may be blocked/clogged. Pressure change in the PCV system or dirt accumulation in the check valves will prevent efficient gas flow. The result will be a low fuel economy due to the gas and oil mixture difference.
3. Air leakage before and after the Intake Air Flow System. This may be leakage along the corrugated hose connecting the turbo and the intake manifold.
4. The PCV pressure control diaphragm may have busted/ruptured. A faulty PCV pressure control diaphragm will affect the pressure difference in the PCV system resulting in a hissing sound.
5. Air filters may be blocked. Dirty air filters may prevent sensors from getting correct readings, therefore, resulting in reading errors.
How Serious Is The P1101 Code On Chevy Cruze?
The P1101 code is mostly not an indicator of a significant problem in your Chevy Cruze. However, it would cause internal problems in your engine if left unchecked for a prolonged period. Also, depending on the severity of the problem, it will result in rough driving, terrible fuel consumption, and power loss.
Moreover, the repair cost for the problem is relatively cheap at around $50 -$60 (applies when you are replacing the PCV regulator system by yourself – which is most of the time).
As a rule of thumb, always make sure you take every warning sign seriously, especially when you don’t know the problem. Early diagnosis and fixes will save you a lot of money down the road and maybe your life too.
Also, make sure to always do regular maintenance on your Chevrolet Cruze. Just because the check engine light isn’t on, it doesn’t mean that your car is running optimally.
How To Diagnose And Fix The P1101 Code Quickly On Any Chevy Cruze
Before you pop the hood and take a look inside, you will need an OBD-II scanner.
These are the step by step procedures you should follow:
1. Use the OBD-II scanner to detect all the trouble codes stored in the car system.
2. Remove the PCV system cosmetic cover. Start the engine and let it run while the car is idle. Place a finger on the opening of the PCV pressure control diaphragm if you notice a hissing sound from it. If the hissing sound stops, you may have found your problem. If that is the case, all you have to do is replace the entire PCV cover since the diaphragm is fixed to it. However, it is advisable to keep diagnosing more problems to see if there is a more significant underlying issue, i.e., faulty PCV check valves.
3. Turn the engine off and locate the corrugated hose connected to the PCV check valve on the intake manifold. The hose is brittle; it may break if not carefully handled. Disconnect the hose from the base. Use a torch to look inside the pathway from which the hose has been disconnected.
4. You may notice an orange or pink like a nipple at the back of the pathway. That is the check valve. If it is not visible, use cotton swabs and rubbing alcohol to clean the region. Check again. If the check valve is not visible, this may be the problem that you were looking for. A replacement part (for the entire intake manifold from a certified seller) and further analysis from a certified mechanic may be required.
5. The next step is to check the PCV hose connected to the two check valves. Without disconnecting the other side, blow air into the hose; it should blow freely. The next step is to suck air back from the hose, after which it should block the airflow. It will need to be replaced if it doesn’t do any of the above. A hissing sound will be present if the hose is leaking while the engine is running.
6. Fix the leaks, if any, and re-run the scanner test to see whether the code is still there. If you followed all of these procedures, your problem should be fixed.
7. If the replacement unit doesn’t fix the problem, you will have to test the PCM to determine if it is terrible. A lousy PCM will have to be replaced, but this would require a qualified professional’s extensive work.
Tips To Help You Avoid Getting The P1101 Code In The Future
1. Regular cleaning and maintenance. Most car troubles can be fixed by a regular cleaning habit and a short, frequent visit to the mechanic.
2. Check for vacuum leaks regularly.
Frequently Asked Questions
How to replace the intake manifold?
The process is simple and straight forward. Please read this article to learn how to do it.
Can I fix the P1101 trouble code by cleaning the PCV?
Sometimes, yes. Carbon build-up and depositions tend to clog pathways and restrict airflow. A regular cleaning schedule and maintenance check may help fix the problem. However, you should make sure to check for any underlying issues even if the problem disappears.
How long can I drive my Chevy Cruze with the P1101 code?
From a statistic standpoint, you would have to reach 50000 – 70000 miles before replacing any of these parts. However, this will depend on the car model, year of make, and usage.
Is fixing the problem worth it? Should I get a better car instead?
You may be tempted to get rid of your vehicle mainly because the problem is likely to occur time and time again. However, the cost of repairing the car is more economical than what you will get by selling it. The critical parts of the vehicle are quite reliable, hence, worth the keep.
Should I buy any generic replacement parts?
No. As mentioned earlier, even the most certified replacement parts will eventually fail. It is advisable to get the most reliable one of them all for a longer life span, in which case you will need the ones from General Motors themselves.