Ford P1518 Code: Intake Manifold Runner Control Stuck Open
Ford's intake runner plates didn't close when commanded, so low-rpm torque suffers. Often a broken linkage.
At a glance
Severity: Low
- Meaning
- Intake Manifold Runner Control Stuck Open
- System
- Fuel & Air Metering · Powertrain
- Safe to drive?
- Yes, short term
- Typical repair cost
- $10–$1,300
- DIY difficulty
- Moderate
Many Ford V6 and V8 engines of the EEC-V era give each cylinder two intake passages, one always open and one fitted with a butterfly plate. The IMRC system keeps those plates closed at low rpm for air speed and torque, then opens them at higher rpm for power. An actuator, usually a small electric motor with a linkage or cable on each bank, moves the plates, and a monitor circuit inside it tells the PCM where they are. P1518 means the PCM commanded the plates closed but saw them still open, or saw no movement at all. Familiar cases include the 4.2 V6 F-150, 3.0 Duratec Taurus, Sable and Escape, and 4.6 DOHC V8 Mustangs and Lincolns, where a popped linkage bushing or a tired actuator motor is the usual story. It is Ford's older equivalent of the generic P2004.
Can I keep driving? Safe to drive; the engine simply loses some low-rpm pull. Expect slightly sluggish launches and a small fuel economy hit, and have it repaired before an emissions test.
How to read P1518
- P Powertrain
- 1 Manufacturer-specific
- 5 Speed, idle & inputs
- 18 Specific fault
Symptoms
- Check engine light on
- Weaker pull from a stop and below about 3,000 rpm
- Slight hesitation when accelerating at part throttle
- Normal behavior at high rpm, where the plates would be open anyway
- Rattle from the intake area if a linkage is loose
Possible causes
Ranked by how often each cause is behind this code (editorial estimate).
- Failed IMRC actuator motor or its internal position switch
- Linkage or cable disconnected, often a worn nylon bushing popped off the plate lever
- Runner plates or shaft seized by carbon and oil deposits
- Wiring or connector fault in the actuator power, control or monitor circuit
- Actuator or cable out of adjustment after intake manifold work
- PCM output or input fault
Diagnosis step by step
Inspect the linkage first
With the engine off, look at the actuator and its link or cable to the plate levers on each bank. A bushing lying loose, a bent rod or a cable off its bracket explains the code immediately.
Tools: Flashlight
Move the plates by hand
Disconnect the linkage at the plate lever and rotate the plates through their travel. They should turn smoothly and spring back; stiffness or a gritty feel means carbon binding in the manifold.
Tools: Pliers
Command the actuator
Run the key-on engine-running output test or use a bidirectional scan tool to cycle the IMRC while watching the lever. No movement with good wiring points to the actuator; jerky or partial travel suggests binding.
Tools: OBD-II scanner
Check power, control and monitor circuits
Check for battery voltage at the actuator connector with the key on, verify the PCM control wire, and watch the monitor signal change state as the actuator moves. A monitor that never changes can set the code even if the plates move.
Tools: Multimeter
Confirm the repair on a road test
Clear the code and accelerate through the rpm range where the plates switch. Pull should feel even from low rpm and the code shouldn't return.
Tools: OBD-II scanner
Where the parts are
- 1Gas cap
- 2Charcoal canister
- 3Purge valve
- 4Vent valve
- 5Fuel pump
- 6Intake manifold
Repair options & costs
| Repair | DIY? | Estimated cost |
|---|---|---|
| Reattach linkage and replace worn bushings | Yes | $10–$90 |
| Replace IMRC actuator | Yes | $150–$450 |
| Clean seized runner plates | No | $150–$450 |
| Repair actuator wiring or connector | No | $80–$250 |
| Replace intake manifold or IMRC housings | No | $500–$1,300 |
Rough US estimates for parts and labor; shop rates vary by region. Not a quote.
Emissions / smog test impact
Will fail
P1518 turns on the check engine light, so the vehicle fails a US OBD emissions test. After the fix, clear the code and complete a drive cycle so the monitors show ready.
Frequently asked questions
Is P1518 the same as P2004?
They describe the same condition, runner control stuck open. P1518 is Ford's older manufacturer code, while P2004 is the standardized code used on later vehicles and other brands.
Can I just leave the runners open?
The engine will run, but you lose low-rpm torque and the check engine light stays on, so you'll fail an emissions test. Wiring the plates open permanently isn't a legal repair.
Why does a small plastic bushing cause a check engine light?
The bushing connects the actuator to the plate lever. When it wears out and pops off, the actuator moves but the plates don't, and the PCM's monitor sees the wrong position.
Will it damage the engine?
No. Stuck-open runners only reduce low-speed torque and slightly change how the engine breathes. It's an efficiency and emissions issue rather than a mechanical risk.
Sources
- Manufacturer public service information (cross-checked)
- Methodology: How We Build Code Pages · Data Sources We Use · Editorial Policy