Fuel and air

P1512 — Intake Manifold Runner Control Stuck Closed (Bank 1)

Severity: medium Drive with care, to a shop

What P1512 means

Many engines use flaps in the intake manifold to change runner length or size: closed for low-rpm torque, open for high-rpm power. The ECU compares the commanded flap position with feedback from the actuator or position sensor. P1512 is set when the bank 1 flaps stay closed when they should open.

Symptoms

  • Check Engine light on
  • Loss of power at mid and high rpm
  • Rough idle
  • Sluggish acceleration
  • Higher fuel consumption
  • Possible limp mode

Possible causes

  1. Carbon buildup on the flaps and runners
  2. Failed electric or vacuum actuator
  3. Vacuum leak or cracked line to the actuator
  4. Binding or worn linkage, shaft, or bushings
  5. Faulty flap position sensor
  6. Wiring or connector fault (open, corrosion, short)
  7. Rarely, an ECU fault

How to diagnose

  1. Scan all codes and review freeze frame data for related faults
  2. Inspect vacuum hoses, solenoid, and vacuum canister for cracks and leaks
  3. Check the actuator connector and harness: power, ground, circuit resistance
  4. Command the actuator with a scan tool and watch whether the linkage moves
  5. Remove the actuator and move the linkage and flaps by hand to check for binding
  6. Inspect the flaps through the intake opening for carbon and shaft play
  7. Check position sensor signal while commanding open and closed
  8. Clear the code and road test after repairs

Common fixes

  • Clean carbon from the flaps and runners
  • Replace vacuum hoses or the control solenoid
  • Replace the actuator or position sensor
  • Repair wiring and the connector
  • Replace the intake manifold assembly if the flap shafts are worn

P1512 on different brands

Land Rover
Defined as the bank 1 intake manifold air control valve being stuck closed.
Mazda · manuals
Defined as the intake manifold air control system stuck closed.
MINI
Tied to the DISA control circuit, where the ECU sees a signal that is too low.
Jaguar
The manufacturer definition lists a low input from the closed throttle position (CTP) switch.
Alfa Romeo
The manufacturer definition lists an idle speed control (ISC) malfunction.
Chevrolet · manuals
The manufacturer definition lists a throttle control unit signal variation.
Hyundai · manuals
The manufacturer definition lists a low signal from the engine coolant temperature sensor.
Subaru · manuals
The manufacturer definition lists low voltage in circuit 2 of the idle air control (IAC) valve.

Questions and answers

What does P1512 mean?

The ECU found the bank 1 intake manifold runner flaps stuck closed. Carbon, a bad actuator, or a vacuum problem are the usual causes.

Can I drive with P1512?

Short trips are usually possible, but power at higher rpm will be reduced. Don't delay repair, since a broken flap can enter a cylinder and damage the engine.

Will cleaning the manifold fix it?

If carbon is the cause, cleaning often helps. Check the actuator and vacuum lines first so you don't clean needlessly.

This is general information about the code. The meaning can differ between makes and models: a scan tool and the repair manual for your car will show the exact cause.