Turbocharger Underboost
The POWERSTROKE-P0299-73 (Power Stroke) diesel fault code means: Turbocharger Underboost. This is a serious severity code.
- Keep driving?
- Short distances only
- DIY difficulty
- intermediate
- Estimated cost
- $50-$1,500 for boot, up-pipe, or wastegate repairs; more if the turbocharger itself is replaced
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Common Symptoms
- Low power / sluggish acceleration
- Black or excessive smoke under load
- Check Engine Light
- Boost leak hiss, turbo whistle, or chuffing
Probable Causes (Ranked by Likelihood)
- Blown or loose intercooler (CAC) boot -- the most common boost-loss cause Very Likely
- Cracked or leaking turbo up-pipes Likely
- Wastegate problem (1999-2003 wastegated turbo) Likely
- Restricted air filter or intake leak Possible
- Failed or sticking turbocharger Possible
- EBP (exhaust back pressure) sensor or tube fault feeding the PCM bad data Possible
Step-by-Step Diagnostic Procedure
Note: the 7.3L PCM normally flags low boost as Ford-specific P1247 (Boost Pressure Low) or P1248 (Boost Pressure Not Detected) rather than the generic P0299 -- scan for those and read freeze-frame data to confirm what actually set.
Smoke- or pressure-test the intake from the turbo through the intercooler (CAC) to the intake manifold. A popped CAC boot causes an instant boost-loss complaint.
Inspect the intercooler boots at both the hot and cold side for splits or loose clamps.
Check the up-pipes for cracks or blown donut gaskets.
On 1999-2003 trucks, verify the wastegate operates and is not stuck.
Check the EBP sensor and its tube for soot plugging if boost reads normal but a code persists.
Frequently Asked Questions
What is P0299 on a 7.3L Power Stroke?
On the 7.3L Power Stroke (1994.5-2003), a turbo underboost condition is normally reported as Ford-specific code P1247 (Turbo Boost Pressure Low) or P1248 (Boost Pressure Not Detected) rather than the generic OBD-II P0299, which Ford used mainly on the later VGT engines (6.0L/6.4L/6.7L). If your scanner shows P0299 on a 7.3L, treat it as an underboost/boost-leak complaint and check the same things: a blown intercooler (CAC) boot, cracked up-pipes, and the wastegate. Pull P1247/P1248 and freeze-frame data to confirm what set.
Can I drive with P0299 on my Power Stroke?
Only drive short distances to get to a repair facility. The truck will be down on power, and continued operation under load can worsen the underlying problem.
How much does it cost to fix?
Most boost-loss fixes on a 7.3L are inexpensive: a re-clamped or replaced intercooler boot can be under $100, and up-pipe or wastegate work runs into the few-hundred-dollar range. Replacing the turbocharger itself is the high end. Diagnostic time alone runs $100-$180 at most independent diesel shops.