OBD-II Code
P1645
Severity
Not yet reviewed
Nobody on our side has assessed this code yet, so we are not going to guess at how serious it is.
Can you drive it
We cannot say
Treat it as unknown until a shop reads it with live data. If the check-engine light is FLASHING, stop driving as soon as it is safe to — that means an active misfire, whatever the code.
Indicative cost (USD)
$0–$900
From this code's diagnostic notes. Varies by vehicle, diagnosis, parts, and local labor. This is not a repair quote.
$0-$50 (top-of-tank wiring repair + heat-shrink) to $900 (full pump module + FPCM + tank drop labor).
P1645 on a Volvo is Fuel Pump Speed Control Range/Performance — on modern Volvos with a returnless variable-speed fuel pump, the ECM commands pump speed via a PWM signal (0-100% duty cycle) to the FPCM (fuel pump control module), and the FPCM reports back actual pump current draw (5-15A typical at moderate load, spiking to 18-20A at WOT on T6 direct-injection).
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 follow the diagnostic notes further down this page, in the order they are written.
They are written in the order a shop works this code, cheapest checks first. Where they name a component, inspect its wiring and connector before replacing it.
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
Read the full diagnostic procedureP1645 on a Volvo is Fuel Pump Speed Control Range/Performance — on modern Volvos with a returnless variable-speed fuel pump, the ECM commands pump sp…
P1645 on a Volvo is Fuel Pump Speed Control Range/Performance — on modern Volvos with a returnless variable-speed fuel pump, the ECM commands pump speed via a PWM signal (0-100% duty cycle) to the FPCM (fuel pump control module), and the FPCM reports back actual pump current draw (5-15A typical at moderate load, spiking to 18-20A at WOT on T6 direct-injection). P1645 sets when commanded duty and reported current diverge past threshold, or when the FPCM reports an open/short on the pump motor circuit.
Cheapest-first ladder
- Read live data — scan tool should show 'Fuel Pump Duty Cycle' and 'Fuel Pump Current'; a duty cycle pinned at 100% with current below 3A means an open circuit (wiring or motor), and a duty cycle ramping normally with current spiking past 18A at idle means a mechanically failing pump dragging on its bearings.
- Check the top-of-tank connector — on Volvo T6 turbo direct-injection cars, the fuel pump module's main connector at the top of the tank is a known wiring-chafe point where the harness rubs the body opening; pull the access cover under the rear seat or trunk floor, inspect the wires for chafe-through, and ohm the pump motor (should read 0.5-2 ohms across the motor terminals).
- Test FPCM ground and B+ feed before condemning the module.
- If the connector and wiring are clean, the FPCM ($180-$350) is more likely to fail than the pump itself ($400-$700) on these cars. Do NOT drop the tank and replace the pump on the first scan — on 2010-2018 XC60 T6 / S60 T6 / XC90 T6 cars, the top-of-tank connector wiring chafe is the most common P1645 cause and the fix is a $0-$30 wiring repair, not a $700 pump.
Vehicle-specific patterns2010-2018 Volvo XC60 T6 / S60 T6 / V60 T6 with the B6304T turbo direct-injection 6-cyl is the most common P1645 platform — the fuel pump module wirin…
- 2010-2018Volvo XC60 T6 / S60 T6 / V60 T6 with the B6304T turbo direct-injection 6-cyl is the most common P1645 platform — the fuel pump module wiring at the top-of-tank connector chafes against the body opening on cars with 80K+ mi, and Volvo issued internal service guidance on the wire-routing fix.
- 2003-2014Volvo XC90 (2.5T or V8) throws P1645 less often because the older port-injection systems use a simpler constant-pressure pump, but when it does it's usually FPCM failure.
- 2008-2016Volvo S80 T6 with the B6304T also shows the top-of-tank chafe pattern.
- 2015-2022Volvo XC90 T6/T8 (second generation, SPA platform) has a different pump architecture and rarely throws P1645 — when it does, suspect the high-pressure pump on the direct-injection rail, not the in-tank lift pump.
Estimated repair$0-$50 (top-of-tank wiring repair + heat-shrink) to $900 (full pump module + FPCM + tank drop labor).
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