OBD-II Code · Fuel & Air
P0629
Fuel Pump A Control Circuit High
Severity
medium
Worth booking. It costs fuel, emissions or comfort until it is fixed.
Can you drive it
Only if running normally
A short trip to a shop may be reasonable if the light is steady and the car runs normally. Stop safely for a flashing light, severe shaking, overheating, loss of power, or another urgent warning. The code alone cannot confirm safety.
Indicative cost (USD)
$100–$500
Varies by vehicle, diagnosis, parts, and local labor. This is not a repair quote.
Fuel pump control voltage high.
How a shop works this
Work from evidence to part, not the other way round. A code names a circuit or a symptom; it does not name the part that failed.
Note every code that is set, not just this one.
Codes that appear together usually narrow the cause faster than any one of them read alone.
Read the freeze frame — the conditions the fault was recorded under.
Cold or warm, idle or load, road speed and engine speed. A fault that only appears cold is a different fault from one that only appears under load, even with the same code on the scanner.
Confirm the fault is current rather than history.
Clear the code and see whether it returns under those same conditions. A code that does not come back may have been logged during a repair, a flat battery, or a bad connection that has since been disturbed.
Then work the likely-causes list in the order shown.
That order is what a shop checks first for this code — wiring and connections before the component they run to, because a connector costs nothing to inspect and is a common answer.
If the code comes back after a repair, the underlying fault is still there. That is the point to bring in a scanner with live data and freeze-frame, or a shop that has one.
Common symptoms
- Check engine light
Likely causes
- Short to powerMost common
- Failed driver
Read the full diagnostic procedureP0629 is the high-side complement to P0628: the FPDM control circuit is reporting battery voltage when the PCM is commanding the line low, or command…
P0629 is the high-side complement to P0628
the FPDM control circuit is reporting battery voltage when the PCM is commanding the line low, or commanded duty cycle is below feedback by more than the manufacturer threshold. In PWM fuel-pump systems the PCM low-side-drives the FPDM control wire; at rest the wire sits near battery voltage (pulled up internally), and the PCM pulls it low to switch the FPDM output on. P0629 sets when the PCM can't pull that line down — either the wire is shorted to a 12V source, the PCM low-side driver has failed open, or the FPDM has internally shorted its control input to its supply. Shop-floor ladder, cheapest first: backprobe the FPDM control wire with a DVOM key-on engine-off; healthy reading is 11-13V with the PCM idle. Then crank the engine while watching: it should drop to 0-2V momentarily as the PCM commands the pump on, with the duty cycle averaging 30-60% during run. If it stays pegged at battery voltage through cranking, disconnect the FPDM connector and check the wire's resistance to chassis ground — anything below 100 ohms is a short-to-power somewhere upstream (almost always chafed against a frame member). Inspect the FPDM connector for green corrosion and bent pins. Expensive-misdiagnosis caveat: P0629 with no fuel pump activity will tempt you toward a PCM replacement, but on Ford trucks the in-tank pump itself has been seen to short its supply line back through the FPDM and pull the control wire high — disconnect the pump at the tank and retest before condemning the PCM, because a $400 pump masquerading as a $1,200 PCM job is a 40% chunk of your margin gone.
Vehicle-specific patterns2011-2016 Ford F-150 EcoBoost is the most common P0629 ticket — same frame-rail FPDM as P0628, but the failure mode here is typically internal short…
- 2011-2016Ford F-150 EcoBoost is the most common P0629 ticket — same frame-rail FPDM as P0628, but the failure mode here is typically internal short rather than corrosion; the FPDM swaps out and the code clears.
- 2009-2014Ford F-150 5.0 Coyote and 5.4 Triton share the same FPDM platform and the same failure.
- 2007-2014Lincoln Navigator and Ford Expedition with the 5.4L 3V throw P0629 from FPDM internal shorts as the modules age past 100k miles.
- 2014-2019RAM EcoDiesel throws P0629 from the under-seat low-pressure pump control module — same root cause, different mounting.
- 2010-2016Lincoln MKT / MKS / Taurus SHO with the 3.5L EcoBoost shares the F-150 FPDM and shares its failure curve.
Estimated repair$200 (FPDM replace DIY) to $1,400 (FPDM + pump + harness section + labor).
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P0629 — frequently asked
What does a P0629 code mean?
Fuel pump control voltage high.
What causes a P0629 code?
Common causes: Short to power; Failed driver.
What are the symptoms of a P0629 code?
Typical symptoms: Check engine light.
Is it safe to drive with a P0629 code?
Only if running normally. A short trip to a shop may be reasonable if the light is steady and the car runs normally. Stop safely for a flashing light, severe shaking, overheating, loss of power, or another urgent warning. The code alone cannot confirm safety. Estimated repair: $100-$500.
How do I diagnose a P0629 code?
Work from evidence to part, not the other way round. A code names a circuit or a symptom; it does not name the part that failed. 1. Note every code that is set, not just this one. 2. Read the freeze frame — the conditions the fault was recorded under. 3. Confirm the fault is current rather than history. 4. Then work the likely-causes list in the order shown.
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