What is Code P0299 Buick Encore
2025-11-19
P0299 Buick:
If you’re dealing with p0299 Buick, whether it’s a 2018 Buick Regal like the one in this case, or common issues like p0299 Buick Encore, 2017 Buick Encore p0299, or even 2016 Buick Encore code p0299, this blog is for you.
I’ll walk through how I diagnosed and fixed an intermittent check engine light with reduced acceleration on a 2018 Buick Regal, plus share insights that apply to other models like the 2013 Buick Encore turbo problems, 2014 Buick Encore p0299, and beyond. Spoiler: The culprit was a faulty turbocharger bypass solenoid, a common trigger for the p0299 code Buick Encore across model years.
I’ll walk through how I diagnosed and fixed an intermittent check engine light with reduced acceleration on a 2018 Buick Regal, plus share insights that apply to other models like the 2013 Buick Encore turbo problems, 2014 Buick Encore p0299, and beyond. Spoiler: The culprit was a faulty turbocharger bypass solenoid, a common trigger for the p0299 code Buick Encore across model years.
Fault Symptoms
I recently had a 2018 Buick Regal with the LFV engine (33,000 km on the odometer) come into the shop. The owner reported two key issues: an intermittent check engine light and poor acceleration response, especially during hard acceleration. Sound familiar? It’s exactly the kind of problem drivers face with the 2015 Buick Encore P0299 or 2017 Buick Encore P0299 code.
During a road test (in manual shift mode), the first hard acceleration felt normal. But on the second attempt, the check engine light lit up, and the car lost power—no more “push” when flooring it. After repeated tests, I noticed the issue only popped up when accelerating hard right after releasing the gas pedal, a pattern I’ve seen with Buick Encore P0299 code cases, too.
Fault Diagnosis
Step 1: Scan for Trouble Codes
Back in the shop, I started with the basics: a diagnostic scan (using a GDS tool). The engine control module (ECM) stored the code P0299 (sometimes misspelled as po299), “Engine Turbocharger Underboost.” This is the same code that appears in the 2016 Buick Encore P0299 and the 2018 Buick Encore code P0299 troubleshooting.
Step 2: Understand the P0299 Setting Condition
From the repair manual, I learned P0299 (or p0299 buick) sets when the ECM detects actual boost pressure is lower than the desired pressure for 3+ seconds. Checking the live data confirmed the issue:
- Desired boost pressure: 137.02 kPa
- Actual boost pressure: Only 35 kPa
That’s a huge gap, explaining the lack of power. For context, this is identical to the data I’ve seen in 2013 Buick Encore turbo problems and 2014 Buick Encore P0299 diagnostics.
Step 3: Inspect Key Turbo System Components
The LFV engine uses a turbocharger system with two critical solenoids:
- Exhaust wastegate control solenoid
- Turbocharger bypass solenoid (recirculates air when the throttle closes to protect the turbo)
I checked:
- Intake hoses and wiring: No loose connections or damage (common in Buick Encore P0299 code cases, but not here).
- Exhaust backpressure: Normal.
- Boost hoses: No leaks (tested with a smoke machine).
- Solenoid drive tests: Both solenoids made a “click” sound when activated, so I initially thought they were working.
- Turbocharger boost sensor: Swapped it with a working one from a demo car, no change (ruled out a sensor issue, which sometimes causes the 2017 Buick Encore P0299).
- Turbo assembly: Took it apart, no damage to turbine/pump wheels, and the wastegate wasn’t stuck.
Step 4: Dig Deeper into the Bypass Solenoid
Since the standard diagnostic steps (per the manual) didn’t fix it, I focused on the turbocharger bypass solenoid, even though it “clicked” during testing. This is a common oversight with p0299 Buick Encore problems: a solenoid can make noise but still fail to retract properly.
When I removed the bypass solenoid, I noticed it occasionally wouldn’t circulate (reset when pressed. That’s the smoking gun! For 2015 Buick Encore P0299 or 2016 Buick Encore code P0299 owners, this is a key component to inspect, even if the drive test seems normal.
Fault Resolution
I replaced the faulty turbocharger bypass solenoid and took the car for multiple road tests. The check engine light stayed off, acceleration was responsive, and the boost pressure matched the desired value (137.02 kPa).
This fix works for more than just the 2018 Regal: I’ve used the same solution for 2014 Buick Encore p0299, 2017 Buick Encore p0299 code, and 2018 Buick Encore code p0299 cases. The bypass solenoid’s intermittent failure meant it didn’t close properly during hard acceleration, so compressed air recirculated inside the turbo instead of going to the engine, causing underboost.
Fault Summary
This p0299 Buick case taught me three valuable lessons (applicable to all models from 2013 Buick Encore turbo problems to 2018 Buick Encore code p0299):
- Don’t trust just the “click”: A solenoid making noise during a drive test doesn’t guarantee it’s working correctly. Physical inspection (checking for smooth retraction) is critical for p0299 code Buick Encore issues.
- Focus on the bypass solenoid: For P0299 (or P299) in Buicks, the turbocharger bypass solenoid is a top culprit, especially for intermittent underboost.
- Follow the data: The gap between desired and actual boost pressure was the key clue. Always cross-reference trouble codes with live data for p0299 Buick diagnostics.
If you’re dealing with p0299 Buick Encore, 2015 Buick Encore p0299, or any Buick with underboost and the P0299 code, start with the turbocharger bypass solenoid. It’s a simple, cost-effective fix that resolves most of these cases.