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P1570

IMRC Circuit High.

  • Mazda
  • Powertrain
  • Manufacturer code
  • Medium severity

How this code is built

P
SystemPowertrain
1
Defined byThe manufacturer
5
AreaVehicle speed, idle control and auxiliary inputs
70
FaultThe specific fault in that area

What it means

On Mazda, P1570 means the powertrain control module has detected a high voltage in the Intake Manifold Runner Control (IMRC) circuit. The IMRC system uses valves or a shutter plate in the intake manifold to change airflow with engine speed and load. The code sets when the control unit sees a circuit voltage higher than expected, which points to a wiring, solenoid, actuator or control unit fault. The exact layout of the system varies by model and engine.

Symptoms

  • Engine warning light on
  • Rough or unstable idle
  • Loss of low-speed torque or flat response
  • Reduced power at higher revs
  • Poor fuel economy
  • Hesitation when pulling away

Possible causes

  • Open circuit or high resistance in the IMRC solenoid or actuator wiringlikely
  • Corroded, loose or damaged connector at the IMRC solenoid/actuator or control unitlikely
  • Faulty IMRC solenoid, vacuum valve or motor actuatorlikely
  • Short to voltage in the IMRC control wirepossible
  • Sticking or seized intake runner valves or shutter plate, or a damaged linkagepossible
  • Faulty power or earth supply to the IMRC circuit, such as a blown fuse or relaypossible
  • Internal fault in the powertrain control modulerare

How to diagnose

  1. Read all stored and pending codes and note the freeze frame data, then check for related codes such as IMRC performance or other circuit faults
  2. Check the IMRC fuse and any related relay for the specific model and engine
  3. Visually inspect the IMRC wiring, connectors and vacuum hoses (if fitted) for chafing, heat damage, corrosion and poor pin tension
  4. Check that the actuator or solenoid moves freely and that the linkage and runner valves are not sticking or carbon-fouled
  5. Test the solenoid or actuator resistance against the manufacturer specification for that engine
  6. Use a scan tool that supports actuator tests to command the IMRC on and off, and listen for or watch the movement
  7. Back-probe the control wire, supply and earth with the circuit active to look for a high voltage, open circuit or short to voltage
  8. Only after the wiring and components are proven good, consider the control module and check for any applicable software update

How to fix

  • Repair or replace damaged wiring and clean or replace corroded connectors
  • Replace the faulty IMRC solenoid, vacuum valve or actuator
  • Clean or replace sticking runner valves, shutter plate or linkage as the engine design allows
  • Replace a blown fuse or faulty relay after finding the cause of the failure
  • Replace or reprogram the powertrain control module only if testing confirms it is at fault

Can I keep driving?

Medium severity

The car can usually be driven for a short time, but it may feel flat and use more fuel. Get it checked soon, as a seized runner valve or a worsening wiring fault could cause further driveability problems.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.

This code for other makes

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