This code means there is a problem with the circuit that controls the turbocharger bypass valve. This circuit controls the boost pressure before it goes into the engine intake pipe.
The diagnostic trouble code (DTC) P0033 may show up if your engine is boosted or supercharged. This article will show what this code means, what makes it happen, what symptoms it might cause, and how to fix it.
What is the P0033 Code?
There is a general OBD-II code called P0033 that works with all cars with a turbocharged or supercharged engine that were made after 1996. This is what the code means:
P0033 Bypass Valve Control Circuit for Turbochargers and Superchargers
The powertrain control module (PCM) keeps an eye on the circuit that controls the turbocharger bypass valve. This circuit has a sensor and an electrical actuator, which can also be called a vacuum control valve. The actuator decides where the bypass valve is located. The bypass valve opens or closes to direct some or all of the exhaust gas away from the turbocharger’s turbine wheel. This changes the boost pressure so that it goes up or down based on the speed and load of the engine. With this information, the sensor tells the PCM where the bypass valve really is.
When the PCM picks up an input signal from the turbocharger bypass valve control circuit that isn’t what was designed, it sets the P0033 code. This could mean that the circuit is open, shorted, or has a voltage that is too high or too low.
What are the Related DTC Codes?
Besides the P0033 code, there are some other DTC codes that are linked to it. These are them:
- P0034 Turbocharger / Supercharger Bypass Valve Control Circuit Low
- P0035 Turbocharger / Supercharger Bypass Valve Control Circuit High
- P0036 Turbocharger / Supercharger Bypass Valve Control Circuit Range/Performance
- P0037 Turbocharger / Supercharger Bypass Valve Control Circuit Intermittent
Some of the more specific problems that these codes show are with the turbocharger bypass valve control circuit are low or high voltage, an out-of-range signal, or a signal that comes and goes.
What are the Causes of the P0033 Code?
Setting the P0033 code could be caused by a number of things. These are them:
- The actuator moves the bypass valve based on orders from the PCM. If the actuator is broken, the bypass valve won’t move. If it’s broken, it might not react right away or at all, sending the PCM the wrong signal or none at all.
- The turbocharger’s bypass valve is broken. The bypass valve is a mechanical part that controls the boost pressure by opening and closing. It might not work right if it is stuck, broken, or leaking, sending the PCM the wrong signal or none at all.
- If the vacuum line is disconnected, cracked, or collapses, it can open or close a bypass valve. Some bypass valves are managed by vacuum instead of electricity. It’s possible for the actuator to lose vacuum pressure if the vacuum line connecting it to the vacuum source is broken, unplugged, or collapsed. This would stop the actuator from moving the bypass valve.
- If the boost pressure sensor is broken, it sends a message to the PCM telling it how much boost pressure is in the intake manifold. If it’s broken, it might send the PCM a signal that isn’t correct or doesn’t exist at all, which would clash with the signal from the bypass valve control circuit.
- Broken or loose connections in the boost sensor circuit: The wire that links the boost sensor to the PCM could be broken or loose because of corrosion, damage, or loose connections. This could make it impossible for the sensor and the PCM to talk to each other, sending either the wrong signal or no signal at all.
- The electrical connections in the boost sensor reference circuit may be loose, corroded, or disconnected. This means that the boost sensor may not be able to connect to its power and ground sources. This could be because of normal wear and tear, moisture, or dirt. This could make the boost sensor circuit lose voltage or ground, which would affect how well it works and what signals it sends.
- PCM or boost controller that doesn’t work right: The PCM or boost controller figures out where the bypass valve should be and tells it to go there using information from different sensors. If it’s broken, it might send the wrong signal or no signal at all to the bypass valve actuator, which would mess up the control system for the bypass valve.
What are the Symptoms of the P0033 Code?
The P0033 code may have different signs based on how bad the problem is and what caused it. These are some of the most common signs:
- Less powerful engine: If the bypass valve isn’t working right, it could change the engine’s boost pressure and air-fuel ratio. This could mean less speed, slower acceleration, and better gas mileage.
- Whining or rattling sounds coming from the turbocharger or turbo pipes: If the bypass valve is stuck, broken, or leaky, it could cause the turbocharger or turbo pipes to make strange noises because of too much or too little boost pressure.
- Too much smoke coming from the exhaust: If the bypass valve isn’t working right, it could let too much or too little air into the engine, which would lead to incomplete burning and more pollution. This could cause the engine to make too much smoke, especially black smoke.
- Poorly working bypass valve: If the bypass valve isn’t working right, it could let too much or too little fuel into the engine, making it rich or lean. This could foul the spark plugs and make them not fire right.
- High temperatures in the engine and/or gearbox: If the bypass valve isn’t working right, it could lead to too much or too little boost pressure, which would affect the cooling systems in the engine and gearbox. This could make the engine and gearbox overheat and break down.
- Hissing sounds coming from the turbocharger wastegate and/or hoses that don’t make sense: If the bypass valve isn’t working right, it could lead to a leak in the wastegate or the hoses that connect it to the bypass valve. One sound that might come from this is air leaving.
- It’s also possible to keep other codes, such as codes related to the turbocharger boost, engine misfire, or knock sensor. These codes show more detailed issues with the turbocharger system, the way the engine works, or the detonation of the engine.
- If it applies, the boost pressure gauge may also show boost pressure values that aren’t normal. It’s possible that this means the bypass valve isn’t controlling the boost pressure properly.
