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.
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.
Manufacturer communications
1Original wording in English
LEXUS
Reported code forms P023400
TSB: REVISION NOTICE August 29, 2017 Rev1: ? Applicability has been updated to include 2017 model year NX 200t vehicles. ? The entire bulletin has been updated. Any previous printed versions of this bulletin should be…
Check vehicle applicability
1A listed vehicle is a research lead. Confirm the engine, production range and software in the manufacturer's information.
| Make | Model | Model year |
|---|---|---|
| Lexus | RC 200T | 2015 |
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 ·
- 22-NA-002 · P0299/P0234 during cold or freezing temperatures ↗
General Motors · PDF page(s) 1 ·
- 2024–2025 MY OBD System Operation Summary for Gasoline Engines ↗
Ford Motor Company · PDF page(s) 86, 87 ·
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.