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DTC codes / Mazda codes / P1252

P1252 · MazdaPressure Regulator Control Solenoid 2 Circuit Malfunction

P1252 on Mazda vehicles indicates that the powertrain control module (PCM) has detected an electrical fault in the circuit for pressure regulator control solenoid 2, which is part of the fuel pressure regulation system. The PCM monitors the solenoid's commanded current and expected response, and it sets this code when the circuit shows an open, short, or out-of-range condition that prevents proper solenoid operation.

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
  • Rough idle or stumbling when the engine is cold
  • Hesitation or flat spots during acceleration
  • Reduced fuel economy due to incorrect fuel pressure regulation
  • Hard starting or extended cranking before the engine fires
  • In rare cases, a rich or lean fuel mixture that may cause surging or misfires

Common causes, most likely first

  1. Failed pressure regulator control solenoid 2, typically due to an open or shorted internal coil
  2. Damaged or corroded wiring harness connector at the solenoid
  3. Broken, chafed, or shorted wire in the circuit between the PCM and the solenoid
  4. Corroded or loose ground connection for the solenoid circuit
  5. Faulty PCM driver for the solenoid circuit, although this is less common
  6. Contamination or mechanical binding inside the solenoid valve that increases current draw

How to diagnose and fix it

  1. Connect a scan tool and verify P1252 is current; record freeze-frame data and check for related codes
  2. Inspect the solenoid connector and wiring for corrosion, loose pins, or obvious damage
  3. Measure the solenoid coil resistance with a multimeter and compare to the Mazda specification for your model
  4. Check for battery voltage at the solenoid connector with the key on and engine off, then check the ground side for continuity
  5. Perform a wiggle test on the harness while monitoring solenoid resistance or scan data to reveal intermittent faults
  6. If the circuit tests good but the code persists, substitute a known-good solenoid and clear the code to see if it returns
  7. As a last step, check PCM connector pins and, if all else fails, verify the PCM driver with a lab scope or known-good PCM

What P1252 really tells you about the fuel system

  • A P1252 can be set by a solenoid that tests fine at room temperature but fails when hot, so always test the circuit both cold and after a test drive.
  • Many technicians replace the solenoid only to find the real problem is a chafed wire behind the intake manifold where it rubs against a bracket.
  • This code does not always mean the solenoid is bad; a poor ground or low battery voltage can trigger it because the PCM sees unexpected current draw.
  • On some Mazda engines, the same solenoid circuit is shared with the purge solenoid ground, so a purge valve fault can set P1252 as a companion code.
  • Clearing the code without repairing the root cause often leads to a comeback because the PCM re-learns the fault within a few drive cycles.

Can I keep driving with P1252?

You can usually drive the vehicle short distances to a repair shop, but avoid heavy acceleration, towing, or long trips because incorrect fuel pressure can cause misfires and damage the catalytic converter. If the engine runs rough or stalls, stop driving and have it towed.

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

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