EngineLightCodes
Powertrain code

P0299 Turbocharger/Supercharger A Underboost Condition

Severity
Fix soon
Typical repair cost
$30–$2,750
Do it yourself
Possible, medium
Shop time
0.5–6 hours

The turbocharger isn't producing as much boost as the engine asked for. The car will feel slow, and the computer may limit power. A leak in the boost hoses or a wastegate problem is more common than a failed turbo.

How the engine computer detects it

P0299 means actual boost stays below target for a period although the control already demands more. Thresholds: GM gasoline 30–55 kPa (4.4–8.0 psi) below target with the warning light in the first trip; GM diesels 10–50 kPa (1.5–7.3 psi), two trips; Ford EcoBoost more than 4 psi (about 28 kPa (4.1 psi)) for 5 s with the wastegate already commanded fully closed; Ford diesels 30–40 kPa (4.4–5.8 psi) for 10–15 s, with a further underboost code P2263. Typical causes from manufacturer bulletins: a charge air leak, a wastegate that lost its preload or whose rod came off, a leaking bypass valve, sticking turbo vanes on diesels, and ice in the charge air cooler in winter. A faulty boost sensor can also fake underboost. Many engines then limit power.

Written from public technical sources and not yet checked by a mechanic. How we write these pages

Symptoms

  • Loss of power, sluggish acceleration
  • Limp mode, power limited
  • Check engine light on
  • Whistling or hissing from the charge air path under load

Common causes

  1. Leak in the charge air path (hose off or torn, cooler leaking, clamps) Most likely
  2. Wastegate faulty (rod off, preload lost, vacuum or solenoid, diaphragm) Most likely
  3. Turbo vanes sticking or turbo worn (diesel) Possible
  4. Bypass valve leaking (torn diaphragm) or its control Possible
  5. Ice in the charge air cooler, boost sensor or connector, or software Less likely

How to diagnose P0299

  1. Inspect the hoses and intercooler between the turbo and the engine for cracks, loose clamps or oil residue.
  2. Check the wastegate or its actuator for free movement, and its vacuum line or solenoid.
  3. Compare desired and actual boost on a scanner during a pull. A gradual gap points to a leak; no boost at all points to the turbo or wastegate.
  4. Check the boost pressure sensor and its connector.
  5. If everything else checks out, have the turbo inspected for shaft play or damaged blades.

Vehicles that report P0299 most

VehicleYearsReportsMedian miles
Buick Encore2016–202113—
Chevrolet Malibu2017–202311—
Chevrolet Cruze2013–20171071k
Chevrolet Trax2015–201910—
Ford Escape2013–20229—
Chevrolet Equinox2018–20249—
Honda Accord2018–20227—
Ford F-1502011–2014669k
Ford Edge2012–20185—
Ram 15002015–2020576k

Counts of owner complaints to the NHTSA that mention P0299 (149 in total), not failure rates: popular models get more complaints simply because more of them are on the road. Models with fewer than 3 complaints are left out.

Reading the code

P
Powertrain
0
Generic (SAE) code
2
Fuel and air metering (injector circuit)
99
Specific fault

Questions drivers ask

Can I drive with code P0299?

Yes, gently. Expect less power. If you hear a loud whine, see blue smoke or lose oil, stop driving: the turbo may be failing.

Will my car pass an emissions inspection with P0299?

Probably not in states that test vehicles with an OBD-II scan: an emissions-related code that keeps the check engine light on is usually an automatic fail. Rules differ by state and county, so check yours.

Can I fix P0299 myself?

Often yes, with an OBD-II scanner and basic tools. Difficulty: medium. Start with the cheapest checks before replacing expensive parts.

Often reported together

Codes that owners mention in the same NHTSA complaints as P0299. They can point to a shared cause, so it's worth checking them together.

This page is general information, not a substitute for a professional diagnosis. Repair costs are rough estimates for parts and labor and vary by vehicle and region.