P0299

P0299: Turbocharger/Supercharger Underboost (Bank 1)

Verify with official recall databases, service records, a mechanic inspection, and local market data before relying on this summary.

At a glance

Quick diagnostic answer

The computer compares requested boost against the manifold pressure sensor. Sustained underboost sets P0299 and usually triggers reduced-power protection.

SeverityModerate UrgencyUrgency not yet verified EvidenceSource notes available
OBD code
P0299
System/category
Turbo/Forced Induction
Severity
Moderate
Structured severity term
Urgency
Urgency not yet verified
Can I drive?
Drive with caution
Usually accompanied by reduced power (limp). Driveable gently, but boost leaks left alone can hide failing hardware.
Repair/cost band
$$$ · Major
Estimate band only — actual cost varies by region, parts availability and labor rates.
Vehicle applicability
Common across modern turbocharged engines; the small-displacement turbo era made it a frequent flyer.
Current applicability note is free text

Computed rule output may be more cautious than stored content and is never used to soften safety-critical risks.

Short answer

P0299 means the engine asked for boost and didn't get it. The cheap causes are leaks in the boost plumbing; the expensive one is the turbo itself — diagnose in that order.

SeverityModerateDrive?Drive with cautionRepairProfessional

Key takeaways

  • The cheap causes are leaks in the boost plumbing; the expensive one is the turbo itself — diagnose in that order.
  • Most common causes: leaking or popped-off boost pipes and intercooler joints and stuck wastegate or failed boost control solenoid.
  • First diagnostic step: pressure-test the boost system — leaks are the most common and cheapest cause.

Can I still drive with this?

Drive with caution

Usually accompanied by reduced power (limp). Driveable gently, but boost leaks left alone can hide failing hardware.

SeverityModerate

Moderate

Diagnostic flow

  1. What it meansThe computer compares requested boost against the manifold pressure sensor. Sustained underboost…
  2. Check this firstPressure-test the boost system — leaks are the most common and cheapest cause
  3. Likely causeLeaking or popped-off boost pipes and intercooler joints
  4. Can you drive?Drive with caution

P0299 is a generic OBD-II code, which means it carries the same core definition on every make — what differs is which causes are most likely on your engine.

Work the diagnostic steps below in order. They are sequenced from cheapest-and-most-common to most expensive, which is exactly the order a fair shop should follow.

Structured DTC reference

What P0299 means

The turbocharger is not producing enough boost

A trouble code identifies the circuit or monitored condition that failed its test. It does not, by itself, identify the failed part or prove the same cause on every vehicle.

Cause categories to discriminate

  • Blown-off boost pipe
  • Stuck wastegate
  • Leaking diverter valve
  • Leaking intercooler
  • Worn turbocharger

These are structured diagnostic hypotheses, not a parts-replacement list. Vehicle context, symptoms, operating conditions, and test results determine which remain supported.

Severity and drivability

The code alone is not enough to assign one universal severity or “safe to drive” answer. Stop driving for loss of braking or steering, severe overheating, oil-pressure loss, a fuel leak or fire risk, or any rapidly worsening safety symptom.

What it means

The computer compares requested boost against the manifold pressure sensor. Sustained underboost sets P0299 and usually triggers reduced-power protection.

Common symptoms

  • Noticeable power loss / limp mode
  • Whoosh or hiss under acceleration
  • Check engine light
  • Occasional oil residue at boost pipe joints

Likely causes

  • Leaking or popped-off boost pipes and intercooler joints
  • Stuck wastegate or failed boost control solenoid
  • Failing turbocharger (worn bearings, damaged vanes)
  • Clogged air filter or intake restriction
  • Faulty boost pressure sensor

Diagnosis steps

  1. Pressure-test the boost system — leaks are the most common and cheapest cause
  2. Inspect every clamp and the intercooler for oil-wet joints
  3. Test wastegate/actuator movement and the control solenoid
  4. Check turbo shaft play only after leaks are ruled out
  5. Verify sensor readings against a gauge

What a mechanic should check

Insist on a boost leak test before any turbo quote — replacing turbos to fix loose clamps is a classic overcharge.

Vehicle applicability

Common across modern turbocharged engines; the small-displacement turbo era made it a frequent flyer.

Repair actions / cost band

$$$ · Major

Estimate band only — actual cost varies by region, parts availability and labor rates.

P0299 — vehicles with official records naming this code

P0299 is named in NHTSA-published manufacturer communications or investigations for 68 vehicle families, including:

A code named in a manufacturer communication means the document refers to it for those vehicles. It is not a diagnosis of any car, and it does not mean the code is common on that vehicle.

Frequently asked questions

Can I drive with P0299?

Gently, yes — the car protects itself with reduced power. Don't ignore it: some causes progress to expensive hardware.

Does P0299 always mean a new turbo?

No. Boost leaks and control faults are far more common than dead turbos. Test first.

Why does it only happen under hard acceleration?

Leaks and weak hardware show up when boost demand peaks — exactly when pressure is highest.

Keep going

Next diagnostic step

Source & evidence notes

  • Code definition per the SAE J2012 generic OBD-II standard; causes and steps reflect widely documented diagnostic practice.
  • No repair prices are stated — the cost band is an estimate range only.