P1247 — Turbo Boost Pressure Low — 7.3 Power Stroke
Turbo Boost Pressure Low
What it means
Ford enhanced code: measured boost (MAP) pressure is lower than expected for the operating conditions. The 7.3L has a fixed-geometry Garrett turbo (a wastegate on some 1999.5+ trucks) and no VGT.1
Most likely causes
- Boost leak at intercooler boots or pipes — Inspect intercooler boots, pipes and clamps for splits, oil saturation or loose clamps that bleed boost before the intake manifold.1
- MAP sensor or hose fault — Check MAP sensor reading vs. barometric pressure at key-on/engine-off and inspect the MAP vacuum hose for cracks, oil contamination or disconnection.1
- Sticking wastegate (1999.5+ trucks) — Verify wastegate actuator rod moves freely and the wastegate valve seats; a stuck-open wastegate bleeds exhaust drive pressure.1
- Exhaust leak ahead of the turbo — Look for leaks at the exhaust manifold, up-pipes and turbo inlet gasket; pre-turbo leaks reduce turbine drive pressure and measured boost.1
- Worn turbocharger — Check shaft play, compressor/turbine wheel damage and oil seal condition; excessive wear reduces boost production.1
How to diagnose
- Verify freeze-frame conditions and confirm low boost with a mechanical boost gauge.
- Inspect all boost plumbing from turbo outlet to intake manifold for leaks, damaged boots and loose clamps.
- Test MAP sensor voltage and compare to a known-good reading; replace or repair hose/sensor as needed.
- On 1999.5+ trucks, check wastegate actuator function and wastegate valve operation.
- Inspect exhaust manifolds, up-pipes and turbo inlet gasket for leaks using visual and audible checks.
- Assess turbocharger shaft play and wheel condition; confirm oil supply/return integrity.
- Clear codes, road test under load and re-evaluate boost pressure and code status.
Common mistake to avoid
Replacing the turbo before smoke-testing the intake. Boost leaks at intercooler boots, end tanks and clamps are a common cause of low power and underboost codes, and they mimic a failing turbo. Source: BD Diesel — 6.7L Power Stroke problems and real fixes.
Parts and tools you may need
- Mechanical boost gauge
- Hand vacuum pump
- Basic hand tools
- Torque wrench
- Safety glasses
- Shop towels
Tools you’ll need
- mechanical boost gauge — Confirms actual manifold boost vs. MAP sensor reading to verify P1247 low boost condition under load.
- digital multimeter — Tests MAP sensor voltage and reference/ground signals to identify sensor or wiring faults causing low boost readings.
- inspection mirror — Allows visual check of up-pipes, exhaust manifolds, and turbo inlet gasket leaks that reduce drive pressure and boost.
- hand vacuum pump — Tests wastegate actuator diaphragm and valve movement on 1999.5+ trucks to detect sticking wastegate causing low boost.
Rough cost and difficulty
| Likely repair | Parts | Shop labor | Who usually does it |
|---|---|---|---|
| MAP/boost pressure sensor | $40–$200 | 0.3–1 hrs | Easy DIY |
| Intercooler boot, clamp or pipe repair | $20–$200 | 0.5–2 hrs | Easy DIY |
| Wastegate actuator or control solenoid | $50–$300 | 0.5–2 hrs | DIY with tools and a manual |
| Exhaust manifold, gasket or up-pipe leak repair | $50–$400 | 2–6 hrs | DIY with tools and a manual |
Typical US independent-shop figures; labor runs about $120–$180 per hour (dealers charge more). Confirm the diagnosis before buying parts.
When to see a pro
If turbocharger replacement or internal engine work is suspected, have a qualified diesel technician evaluate and perform repairs.
Check for recalls
Recalls are tied to your truck’s VIN, so check yours directly: enter the VIN at NHTSA’s recall lookup. Open safety recalls are repaired free at a dealer.
Sources
Repair videos: P1247 on the 7.3 Power Stroke
Third-party videos, not ours — picked for this engine. Confirm anything against the factory service information for your truck.
Spotted an error, or something missing? Tell us
Run a 7.3 Power Stroke? This goes straight to the editor — it is not published.