01 Ford F-150: The King of Trucks or a Mere Pretender? • 02 Engineers Reveal Why Most Car Doors Are Designed To Rip Apa… • 03 Top Reasons 8 Your Key Won't Turn in the Ignition & Easy Fi… • 04 What Happens When Car Safety Systems Fail • 05 This Is Why Your Car’s Battery Terminals Are Corroded • 06 P0010 A Camshaft Position Actuator Circuit (Bank 1) • 07 The Complete Guide to the Major Parts of an Excavator • 08 Is Using Sport Mode All the Time Bad for the Engine or Just… • 09 Unleashing the Power of Variable Geometry Turbochargers: A … • 10 How to Fix an Alternator that is Draining a Car Battery •

DTC codes / Toyota codes / P1200

P1200 · ToyotaFuel Pump Relay Circuit

P1200 on Toyota vehicles indicates that the engine control module (ECM) has detected an abnormal condition in the fuel pump relay circuit, which controls power to the fuel pump. The ECM monitors the circuit for expected voltage or continuity and sets this code when the signal does not match its programmed parameters, often due to a faulty relay, wiring issue, or ECM driver problem.

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

Symptoms you may notice

  • Engine cranks but fails to start or starts then stalls immediately
  • Intermittent no-start condition, especially after the vehicle sits or in hot weather
  • Engine may stumble or lose power under load if the relay contacts are marginal
  • Audible click from the relay area may be absent when the key is turned to ON
  • Often no symptoms besides the warning light if the circuit fault is intermittent

Common causes, most likely first

  1. Failed fuel pump relay (open or high-resistance coil, pitted contacts)
  2. Corroded, loose, or damaged wiring or connectors in the fuel pump relay circuit
  3. Blown fuse or fusible link supplying the relay
  4. Faulty ECM driver circuit for the fuel pump relay
  5. Poor ground connection for the relay or fuel pump circuit
  6. Aftermarket alarm or remote start system improperly spliced into the fuel pump circuit

How to diagnose and fix it

  1. Verify battery voltage and inspect the fuel pump relay fuse and fusible link for continuity
  2. Locate the fuel pump relay and perform a click test and coil resistance check per Toyota service information
  3. Inspect relay socket terminals and wiring for corrosion, looseness, or chafing, and repair as needed
  4. Swap the fuel pump relay with a known-good identical relay and clear the code to see if it returns
  5. Check for voltage at the fuel pump connector during cranking to confirm relay operation
  6. Test the ECM control signal at the relay coil with a test light or oscilloscope to rule out a driver fault
  7. If all external circuits test good, follow Toyota diagnostics for ECM replacement or reprogramming

Relay Circuit Checks Before ECM Replacement

  • A common oversight is assuming the fuel pump itself is faulty when the relay circuit is the actual problem; always confirm relay operation before dropping the tank.
  • Intermittent P1200 codes often trace to a relay that tests fine at room temperature but fails when hot, so a cold resistance check alone can miss the fault.
  • Aftermarket accessories such as alarms or remote starters spliced into the fuel pump wiring are a frequent cause of this code on older Toyota models.
  • The ECM may set P1200 even when the engine runs normally if the relay feedback signal is momentarily out of range, so do not replace the ECM without confirming the circuit integrity.
  • Corrosion inside the relay socket can create enough resistance to set the code without any visible damage, so inspect the terminals closely with a bright light.

Can I keep driving with P1200?

If the engine starts and runs normally, you can drive to a repair shop, but avoid long trips or situations where a stall would be dangerous. If the engine cranks but does not start or stalls repeatedly, do not drive and have the vehicle towed to prevent being stranded.

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 Toyota vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

Running on fumes Free guides aren't free to make. Top up the tank. Any amount, one time. Fuel the Garage