Faulty fuel pump control module (also called fuel pump driver module) mounted near the fuel tank; Damaged or corroded wiring harness between the PCM and fuel pump control module; Failed fuel pump with excessive current draw or open windings; Blown fuel pump fuse or tripped fuel pump relay in the engine compartment fuse box; Poor electrical ground connection for the fuel pump control module or fuel pump; Corroded electrical connector at the fuel pump assembly or control module; PCM software issue or internal driver fault (rare, but possible after other causes are ruled out)

DTC codes / Mazda codes / P1235

P1235 · MazdaFuel Pump Control Circuit

Q: What does code P1235 mean?

Fuel Pump Control Circuit. P1235 on Mazda vehicles indicates that the powertrain control module (PCM) has detected an abnormal condition in the fuel pump control circuit, which manages electrical power to the fuel pump. The PCM monitors the circuit for expected voltage or current feedback and sets this code when the signal falls outside the programmed range, often due to a wiring fault, a failing fuel pump control module, or a pump drawing excessive current.

P1235 on Mazda vehicles indicates that the powertrain control module (PCM) has detected an abnormal condition in the fuel pump control circuit, which manages electrical power to the fuel pump. The PCM monitors the circuit for expected voltage or current feedback and sets this code when the signal falls outside the programmed range, often due to a wiring fault, a failing fuel pump control module, or a pump drawing excessive current.

SystemPowertrain

Code typeMazda 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
Engine cranks but fails to start or starts only after prolonged cranking
Engine stalls shortly after starting or during deceleration
Loss of power or hesitation under acceleration due to inadequate fuel delivery
Intermittent no-start condition that may be temperature or vibration sensitive

Common causes, most likely first

Faulty fuel pump control module (also called fuel pump driver module) mounted near the fuel tank
Damaged or corroded wiring harness between the PCM and fuel pump control module
Failed fuel pump with excessive current draw or open windings
Blown fuel pump fuse or tripped fuel pump relay in the engine compartment fuse box
Poor electrical ground connection for the fuel pump control module or fuel pump
Corroded electrical connector at the fuel pump assembly or control module
PCM software issue or internal driver fault (rare, but possible after other causes are ruled out)

How to diagnose and fix it

Verify battery voltage and inspect the fuel pump fuse and relay; replace any blown fuse or faulty relay
Perform a visual inspection of the fuel pump control module and its connectors for corrosion, water intrusion, or damaged pins
Check for diagnostic trouble codes (DTCs) in other modules and review freeze-frame data to understand when the fault occurred
Measure resistance and voltage drop on the fuel pump control circuit wiring while wiggling the harness to reveal intermittent faults
Command the fuel pump on with a scan tool and listen for pump operation; measure current draw with a clamp meter to compare against specification
If the control module is suspect, test its output signal with an oscilloscope or substitute a known-good module before replacement
After repairs, clear codes and verify the fuel pump control circuit operates correctly during a road test with live data monitoring

What Mazda techs check before replacing the pump

A corroded ground connection on the fuel pump control module can mimic a failed module, so always check ground integrity before condemning parts.
The fuel pump control module on many Mazdas is located under the rear seat or near the fuel tank and is prone to water damage from clogged sunroof drains or rear washer leaks.
P1235 can be set by a fuel pump that is beginning to seize, drawing higher current than normal without completely failing, so current waveform testing is more reliable than a simple voltage check.
Intermittent P1235 codes that appear only on hot days or after long drives often point to a failing fuel pump control module rather than wiring, because heat increases resistance in the module's internal circuits.
Some Mazda models use a variable voltage fuel pump control system, and a scan tool that can command different pump duty cycles is essential to properly diagnose the circuit without guesswork.

Can I keep driving with P1235?

If the engine starts and runs normally, you can drive cautiously to a repair shop, but avoid hard acceleration and long trips because the fuel pump may stop without warning. If the engine cranks but does not start or stalls repeatedly, do not drive and have the vehicle towed to prevent a dangerous stall in traffic.

Tools that help

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