Reference meaning
What does this code mean?
The boost-control monitor detects excessive boost for the calibrated operating condition. P0234 is overboost; P0299 is underboost. Their appearance together does not make them synonymous. The cited Ford monitor and Audi DTC chart distinguish them; thresholds and enable conditions remain engine-specific.
Sources and interpretation [1] [3]
A code identifies a detected condition, not a part that must automatically be replaced.
Narrow by vehicle
A listed vehicle is a research lead. Confirm the engine, production range and software in the manufacturer's information.
Manufacturer example · limited applicability
GM 22-NA-002 covers 2018–2022 Equinox/Terrain 1.5L LYX in the US/Canada and links cold-weather codes to moisture/ice and boost control. Its first-page list labels P0234 as underboost; that conflicts with the Ford/Audi overboost definition. We use it for the scoped cold-weather example, not to redefine P0234.
Before replacing a part
Preserve load, temperature and desired/actual boost data. Use the vehicle's actuator and pressure-control checks before replacing the turbo. Do not apply a universal wastegate adjustment or boost limit from another engine.
Scan worksheet →Manufacturer wording
Source wording can vary by vehicle and suffix. It is shown as written, not as a universal diagnosis.
P0234-00Turbocharger Overboost Condition
P0234Turbocharger Overboost Condition
P0234Engine Overboost
Manufacturer communications
96Original wording in English
RAM
Air Handling Performance Test (APT) Availability In wiTECH Technicians may experience a Malfunction Indicator Lamp (MIL) illumination and the vehicle may SYMPTOM: exhibit/set one or more of the following Diagnostic Trouble Codes (DTCs): ● P0234-00 - Turbocharger Overboost Condition. ● P0299-00 - Turbocharger Underboost. ● P0101-…
RAM
Air Handling Performance Test (APT) Availability In wiTECH Technicians may experience a Malfunction Indicator Lamp (MIL) illumination and the vehicle may SYMPTOM: exhibit/set one or more of the following Diagnostic Trouble Codes (DTCs): ● P0234-00 - Turbocharger Overboost Condition. ● P0299-00 - Turbocharger Underboost. ● P0101-…
RAM
Flash: Powertrain Control Module (PCM) Updates V2C Customers must experience a Malfunction Indicator Lamp (MIL) illumination and the vehicle must exhibit/set one or more of the following Diagnostic Trouble Codes (DTCs): ● P06B9-00 - Cylinder 1 Glow Plug Circuit Performance. ● P06BA-00 - Cylinder 2 Glow Plug Circuit Performance. …
RAM
Flash: Powertrain Control Module (PCM) Updates V2C Customers must experience a Malfunction Indicator Lamp (MIL) illumination and the vehicle must exhibit/set one or more of the following Diagnostic Trouble Codes (DTCs): ● P06B9-00 - Cylinder 1 Glow Plug Circuit Performance. ● P06BA-00 - Cylinder 2 Glow Plug Circuit Performance. …
Check vehicle applicability
768A listed vehicle is a research lead. Confirm the engine, production range and software in the manufacturer's information.
| Make | Model | Model year |
|---|---|---|
| Audi | A4 ↗ | 2012 |
| Audi | A4 ↗ | 2011 |
| Audi | A4 ↗ | 2010 |
| Audi | A4 ↗ | 2009 |
| Audi | A4 AVANT ↗ | 2012 |
| Audi | A4 AVANT ↗ | 2011 |
| Audi | A5 ↗ | 2012 |
| Audi | A5 ↗ | 2011 |
Sources and interpretation
These explanations are editorial summaries of the linked manufacturer material. PDF page numbers count from the first file page. Original publications are in English; translations are reference aids. A cited edition is not a claim that it is the manufacturer's latest instruction.
- Audi TT Quick Reference Specification Book · October 2013 ↗
Audi of America · PDF page(s) 135 · 2013-10
- 22-NA-002 · P0299/P0234 during cold or freezing temperatures ↗
General Motors · PDF page(s) 1 · 2022-02
- 2024–2025 MY OBD System Operation Summary for Gasoline Engines ↗
Ford Motor Company · PDF page(s) 86, 87 · 2024-04-16
Source check date · 2026-10-27
Can I keep driving?
A code alone cannot establish whether driving is safe. A flashing malfunction light, severe shaking, overheating, oil-pressure warning or loss of braking or steering needs prompt attention. Stop in a safe place and seek assistance when control or engine safety is affected. Follow the vehicle handbook.