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P0299 Volkswagen Fault Code: Turbo/Super Charger Underboost Condition
Receiving a P0299 VW code with an OBD-II scanner will typically read “Turbo/Super Charger Underboost Condition”. When this fault code appears with a Check Engine Light (CEL), unfortunately, it is hard to diagnose. This fault code is the most common on Volkswagen and Audi 2.0T engines. A P0299 fault code means that the turbocharger, or supercharger in other engines, has excessively low output. The ECU sets a specific range of optimal boost levels and when low boost is detected, a CEL will illuminate accompanied with a P0299 fault code.
VW TT 21-10-02
Volkswagen issued a Tech Tip to address this fault code with specific models and engines. Originally issued in 2010 and last updated in 2015, Volkswagen issued Tech Tips for all 2008-2015 vehicles with the CCTA or CBFA 2.0l TSI engines. Essentially Volkswagen found that a roll pin, located in the 2.0 TSI turbochargers exhaust housing, might eventually back out. When the roll pin backs out it causes the wastegate valve and lever to drop into the turbo’s exhaust housing. Once it goes into the housing, the wastegate lever and be stuck in the closed (overboost – P0234) or open (underboost – P0299) position. Given that the P0299 indicated an underboost condition, the wastegate lever is stuck in the open position.
The Tech Tip is to check if the wastegate lever has approximately 3mm of clearance from the bottom of the lever and the housing, pictured here. Unfortunately, if there is no gap, the whole turbocharger has to be replaced. I would assume if your vehicle happens to be in the model years given with the specific engine, you should be covered by Volkswagen. However, we are not 100% certain that is the case, so if you feel like you qualify, it would be best to show the Tech Tips bulletin above to a local dealership and hope they cover it.
P0299 VW Symptoms
- Check Engine Light (CEL) or Malfunction Indicator Lamp (MIL) illuminating
- Limp mode activated
- Loss of power
- Hissing, whining, or rattling noise coming from the engine bay
Causes of P0299 Engine Code for Volkswagen
- Failing diverter valve (dv), also referred to as a recirculation valve
- Faulty charge air pressure sensor/boost pressure sensor
- Faulty N249 valve
- Possible vacuum leaks or faulty PCV valve
- Faulty N75 valve (wastegate bypass regulator valve)
- Faulty turbocharger or supercharger
How to Diagnose & Repair a Volkswagen with a P0299 Engine Code
Before going into diagnosing and repairing a Volkswagen or Audi with a P0299 fault code, we highly suggest owning an OBD-II scanner to be able to self-diagnose CEL’s that pop-up. It could end up saving you hundreds in diagnosing fees. Receiving a P0299 fault code is not very simple to diagnose and there could be many things that could be causing it. Depending on what could be causing this code, it could cost anywhere from $125 – $3,500. The worst-case scenario is having to replace the turbocharger with a new one, but it could be covered under VW or Audi.
Since the P0299 fault code is most common in the 2.0 TSI engine, we will be listing all replacement parts for that engine. Be sure it fits your exact vehicle before ordering anything. If you need assistance in looking for replacement parts or DIY guides for another engine, let us know in the comments and we will assist in any way we can.
Replace the Diverter Valve or Recirculation valve
The first thing that can be checked is the diverter valve, often referred to as a DV. A diverter valve is a boost pressure release valve that “diverts” unused boost back into the engine to avoid compressor surge. Put simply, it is a valve that opens and closes to sustain boost pressure. DV’s are common to go out on tuned vehicles because of the increase in boost pressure. That’s why when it comes to tuned vehicles, we highly advise replacing the factory dv with an aftermarket dv to sustain the increased boost.
If you are looking to get the dv replaced by a mechanic or local dealer, it would cost around $200. Or DIYing this, is not too difficult and could save up to $150 in labor costs. There are many DIY videos on this and shouldn’t take much longer than an hour.
Replace the Charge Air Pressure Sensor/Boost Pressure Sensor
If the diverter valve doesn’t make the CEL go away, next we would advise looking at the charge air pressure sensor, also called a boost pressure sensor. A boost pressure sensor reports to the ECM how much boost the turbocharger, or supercharger in some engines, is actually producing. Typically, a charge air pressure sensor is found between the intake manifold and turbocharger. However, it can be found on the intake manifold in other engines. Another common fault code this cold throw is P0236 VW.
If you are looking to get the boost pressure sensor replaced by a mechanic or local dealer, it would cost around $250. However, DIYing this would save $125 in labor costs. Depending on where the sensor is located, it is a straightforward DIY and shouldn’t take very long.
DIY Difficulty: Easy to Intermediate
Buy Here: 2.0 TSI Boost Pressure Sensor Replacement
Change the N249 Valve
If replacing both of the above does not remove the P0299 code, next on our list to look at is the N249 valve. The N249 valve can often be referred to as a boost pressure control valve, turbocharger recirculating valve, turbocharger bypass valve, diverter valve control solenoid. It is a part that, like the dv, regulates boost pressure. Common fault codes seen when the N249 valve is failing are P1200, P2261, or P1287. There are two options when it comes to the N249 valve failing: you can either replace it or delete it. We don’t recommend deleting, but there are DIYs out there to do so.
A local dealer or mechanic will charge around $250, but it is a pretty simple DIY if you happen to know your way around the engine.
DIY Difficulty: Easy
Check for Vacuum Leaks or Replace the PCV Valve
Vacuum leaks and PCV valve are common problems on most 2.0 TSI engines. Therefore, don’t be surprised if either is the problem. Vacuum hoses create suction and bring air into the engine. They are difficult to diagnose but will lead the engine to lean AFR conditions. A Positive Crankcase Ventilation valve, or PCV valve, regulates emissions by bringing the gas particles from the crankcase to the engine’s combustion chambers where the gases are safely burned.
If the issue happens to be a vacuum hose leaking, this could be difficult to DIY and would be a costly diagnosis. However, if you are lucky, and it is the PCV valve, it’s a pretty simple DIY. To replace the PCV valve, a mechanic or local dealer would likely charge around $250 – $300.
Buy Here: PCV Valve Replacement
DIY Difficulty: Intermediate
Replace the N75 Valve
Lastly, if none of the above clear the code, the N75 valve could be the last-ditch effort. The N75 valve can also be referred to as a wastegate frequency control valve. The N75 valve is controlled by the vehicle’s ECU to control how much boost the turbo has to create. It is a crucial component for controlling boost in a turbocharger. Although not very common, this could cause a P0299 fault code if not functioning properly.
If you plan on taking your vehicle to the shop to replace this, expect a bill of around $300. However, if you are engine savvy and want to DIY it, it could save a couple hundred bucks.
Buy Here: N75 Valve Replacement
DIY Difficulty: Intermediate
Replace the Turbocharger or Supercharger
If none of the above have alleviated the issue, it may be time to take it to the dealership or a mechanic to get it checked out. Because it very well could be the worst-case scenario, needing a new turbo. Again, I’m sure this can be argued and covered by Volkswagen IF the vehicle is within the model years listed in the TT above. However, if not in those model years, it very well could not be covered if you are outside of your warranty.
P0299 VW/Audi Conclusion
To conclude this post, a P0299 engine code for a Volkswagen or Audi can be driven on for a short period of time. However, if the vehicle enters limp mode, it may be a good idea to take it to the shop. A quick diagnose of the dv, boost pressure sensor, N249 valve, PCV valve, vacuum hoses, and N75 valve should yield a solution to the code. However, if none of those work, it is more than likely a faulty turbo. Let us know your experience with the P0299 VW code in the comments below to assist other future readers.
If you are looking to read up on more Volkswagen or Audi fault codes, here is an article on P2015 VW fault code.