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DTC codes / Chrysler codes / P1287

P1287 · ChryslerFuel Injection Pump Controller Supply Voltage Low

P1287 on a Chrysler vehicle means the engine computer has detected that the supply voltage feeding the fuel injection pump controller circuit has dropped below the acceptable threshold. The controller is the electronic module that manages fuel delivery on the diesel injection pump, and when its power feed is low the computer cannot trust the pump to meter fuel correctly, so it sets this code and may limit engine performance.

SystemPowertrain
Code typeChrysler specific
SeverityMedium
Fix difficultyIntermediate
AreaFuel and air metering (injector circuits)

Symptoms you may notice

  • Illumination of the check engine light, often with no other noticeable symptoms at first
  • Engine may crank but fail to start, or start and then stall shortly after
  • Reduced engine power or limp mode, especially under acceleration or load
  • Rough idle or misfire-like shuddering because fuel delivery is inconsistent
  • Intermittent stalling while driving or when coming to a stop
  • Hard starting when the engine is cold or after the vehicle has sat for a while

Common causes, most likely first

  1. A weak or failing battery that cannot maintain stable voltage under load
  2. Corroded, loose, or damaged wiring and connectors between the battery, fuse box, and fuel injection pump controller
  3. A blown or partially melted fuse in the controller supply circuit, often caused by a short or high resistance
  4. A failing fuel injection pump controller that draws excessive current or has an internal voltage regulator fault
  5. Poor ground connection at the controller mounting point or engine block, raising resistance in the supply circuit
  6. A faulty ignition switch or relay that interrupts voltage to the controller circuit intermittently
  7. Alternator output that is low or erratic, leaving the controller supply below threshold during normal driving

How to diagnose and fix it

  1. Perform a battery load test and check charging system output to rule out a weak battery or alternator before touching the controller circuit
  2. Inspect and clean the battery terminals, the controller supply fuse, and the controller ground connection, then clear the code and retest
  3. Back-probe the controller supply voltage at the connector with the key on and engine cranking, looking for a drop below the specified threshold
  4. Check for voltage drop across the supply wiring and connectors using a multimeter while the circuit is loaded, repairing any high-resistance section
  5. Inspect the fuel injection pump controller connector pins for corrosion, pushed-back terminals, or melted plastic that indicates overheating
  6. If supply voltage is correct at the controller but the code persists, test the controller with a known-good unit or follow the manufacturer's diagnostic flow for internal faults
  7. After repairs, clear the code and verify with a road test that the supply voltage stays stable and the code does not return

What a low supply voltage really points to

  • A battery that starts the engine fine can still set P1287 because the controller supply circuit is sensitive to voltage sag under load, so a load test matters more than a simple voltage reading at rest.
  • The fuel injection pump controller on Chrysler diesels shares its supply with other engine management circuits, so a fault in a neighbouring component can drag the voltage down and trigger this code without any problem in the controller itself.
  • Technicians often replace the expensive fuel injection pump controller when the real fault is a corroded ground strap or a fuse box terminal that has lost tension, so always prove the supply circuit before condemning the module.
  • Intermittent P1287 codes that appear only on cold mornings or after sitting overnight frequently trace to a battery that is nearing the end of its service life rather than a wiring fault.
  • This code can be stored alongside glow plug or injector codes because low supply voltage affects several engine management circuits at once, so read all stored codes before deciding on a repair path.

Can I keep driving with P1287?

You can drive cautiously to a repair shop if the engine runs normally and the light is steady, but avoid heavy acceleration, towing, or long trips because a low supply voltage can cause sudden stalling or limp mode. If the engine stalls, runs rough, or the light flashes, stop driving and have the vehicle towed to prevent damage to the injection pump.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

Guidance is general and written for Chrysler vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

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