Fix P0661: Mechanic’s solutions that WORKED

The code P0661: Intake Manifold Tuning Valve Control Circuit Low indicates a fault in the Intake Manifold Tuning Valve Control Circuit, typically caused by issues with the valve itself, wiring problems, or vacuum leaks. Addressing this code is important as it can significantly impact engine efficiency and performance.

P0661 quick overview

Meaning	P0661: Intake Manifold Tuning Valve Control Circuit Low
Is it serious?	Yes, it can be serious as it affects the engine’s air-fuel mixture and overall performance.
Possible causes	– Faulty Intake Manifold Tuning (IMT) valve or solenoid – Wiring or connector issues related to the IMT valve – Vacuum leaks affecting the IMT system – ECM (Engine Control Module) software needing an update – Faulty ECM
How to diagnose?	Scan for Additional Codes: Check for other codes that might be present alongside P0661. Inspect Wiring and Connectors: Examine the wiring and connectors to the IMT valve for damage or corrosion. Test IMT Valve/Solenoid: Perform electrical and mechanical tests on the IMT valve or solenoid to ensure proper operation. Check for Vacuum Leaks: Inspect the intake system for any signs of vacuum leaks that can affect valve operation. Evaluate ECM Software: Ensure ECM software is up-to-date; reflash if necessary. Assess ECM Functionality: If other steps don’t resolve the issue, consider evaluating the ECM for faults.

In simpler terms, when you see the P0661 code, it means there’s a problem with a part of your car’s engine that helps control how air is taken in. This issue can make your car run poorly and should be checked out to keep your engine running smoothly.

How to fix P0661 – learn from mechanics

I looked into P0661 service cases at iatn.com website where in the private forums the mechanics seek advice from other mechanics. I looked up a bunch of cases to help you decide how to fix your issue and see what would a real mechanic do to solve it.

Case #1: Mazda

Vehicle Information

• 2004 Mazda 3 i, 2.0L

Issue + Repair History

• Hesitation/surging at higher cruising speeds (80-100km/h)
• CEL has been on intermittently, now stuck on for about a week
• P0661 code active for a long time but not causing CEL
• Replaced spark plugs, clutch, cleaned fuel injection system, replaced MAF sensor, cleaned throttle body

Computer Codes & Descriptions

• P2178: System too rich off idle B1
• P2188: System too rich at idle B1
• P0661: Intake manifold tune valve control low B1

Community Suggestions

• Check TSB 01-006/06 for guidance on the issue
• Consider replacing the intake manifold as per TSB 01-012-09
• Check for a stuck open purge valve or saturated canister
• Inspect secondary air valves in the engine for looseness or lodging

Final Fix

• Cleaning the intake manifold/throttle body and clearing codes resolved the issue temporarily

Case #2: Honda

Vehicle Information

• 2004 Honda CR-V EX, 2.4L

Issue + Repair History

• Intermittent no-start, misfire codes (P0300, P0301, P0302)
• Previously active code P0661 (IMRC Valve Control Low Voltage)
• Replaced IMRC solenoid, runner valve assembly, A/F sensor
• Checked IMRC position valve and sensor, new NGK spark plugs and coil packs installed 10,000 miles ago

Computer Codes & Descriptions

• P0661: Intake Manifold Runner Control Valve Position – Low
• P0300: Random/Multiple Cylinder Misfire Detected
• P0301, P0302: Misfire Detected in Cylinder 1, 2

Community Suggestions

• Check wiring and voltage at IMRC sensor
• Conduct compression test and adjust valves if necessary
• Inspect wiring harness for issues
• Investigate potential IMRC valve or sensor problems
• Ensure good ground and 5-volt reference to IMRC sensor
• Consider if VTEC system is affecting valve behavior

Final Fix

• Resolved no-start condition by addressing issues with splice pack C103 and PGM-F1 Main Relay 1
• Replaced IMRC solenoid and valve, A/F sensor to resolve P1077 and P0661 codes
• Customer agreed to further diagnosis for splice pack, and valve adjustment scheduled for later

Case #3: Hyundai

Vehicle Information

• 2010 Hyundai Sonata GLS, 2.4L

Issue + Repair History

• MIL Lamp on with codes P2004 (Intake manifold runner stuck open) and P0661 (Intake manifold tuning valve control circuit low)
• Initially had a code for canister vent; resolved by replacing vent filter

Other OBD2 Codes + Test Results

• P2004 and P0661
• Resistance of solenoid checked and within specs
• Scan tool operation of sol and actuator showed proper functioning

Community Suggestions

• Check freeze frame data for error conditions
• Inspect for intermittent short in wiring, or wiring harness issues
• Consider potential carbon plugging in runners or rodent damage to harness
• Test solenoid resistance and check for voltage changes while actuating the solenoid
• Inspect for physical damage or malfunction in runner actuator or intake manifold

Final Fix

• Solenoid replaced after finding it sticks when cold
• Car left overnight, retested next day, and worked properly
• MIL Lamp off and no recurring issues after the replacement

Case #4: Mazda

Vehicle Information

• 2004 Mazda 3 i, 2.0L

Issue + Repair History

• MIL Lamp on with code P2187 (fuel system too lean at idle) and P0661 (variable intake-air solenoid circuit low input)
• Previously replaced HO2S sensor, conducted fuel system cleaning, and replaced spark plugs

Other OBD2 Codes + Test Results

• Fuel pressure: 59 psi (within 55-61 psi spec)
• Ignition system: Replaced spark plugs, gap checked
• Intake system: No vacuum leaks found on smoke test
• Compression test: Cylinder 1 at 120 psi, others at 175-180 psi
• MAF sensor: 2-2.5 g/s at idle, increasing with throttle

Community Suggestions

• Prioritize fixing intake air solenoid code (P0661) to address lean condition
• Check air cleaner box for appropriate type and MAF sensor function
• Investigate potential vacuum leak around #1 intake port
• Consider purge control valve issues causing intermittent sticking
• Test purge solenoid valve, check if it holds vacuum
• Look at wiring and grounds, particularly at MAF sensor
• Adjust valve clearance, especially for low compression in Cylinder 1

Final Fix

• Replaced purge flow control solenoid and variable intake runner control solenoid
• Drove OBD drive cycle for EVAP system, all monitors set with no codes
• Car returned to customer with no further issues reported

Case #5: Mazda

Vehicle Information

• 2004 Mazda 3 i, 2.0L

Issue + Repair History

• Initially had codes P0441, P0442, P0661, and later P2187 (system lean at idle)
• Customer complained of almost stalling at stop lights and surging at 60-70 kph (35-45 mph)
• Performed various checks including MAF sensor cleaning, vacuum leak check, and oxygen sensor operation check
• Long Term Fuel Trim (LTFT) approximately 20%

Other OBD2 Codes + Test Results

• P0441: EVAP purge control fault
• P0442: EVAP small leak
• P0661: Variable intake-air solenoid circuit low input
• LTFT: 20%

Community Suggestions

• Consider the impact of EVAP system on lean condition and surging
• Check purge solenoid for sticking (common in this model)
• Test EVAP purge valve by applying vacuum
• Inspect for vacuum leaks, including the PCV hose
• Consider recalibration for various drivability issues
• Evaluate purge solenoid sticking open, causing lean and EVAP codes

Final Fix

• Replaced the sticking purge solenoid for the EVAP system
• After replacing, the surging problem and lean condition were resolved

Advice	Description of Diagnostic Step
Check the IMT Valve/Solenoid	Verify the operation of the Intake Manifold Tuning (IMT) valve or solenoid.
Inspect Wiring and Connectors	Examine wiring and connectors to the IMT valve for damage, corrosion, or looseness.
Look for Vacuum Leaks	Check for vacuum leaks in the intake system which could affect the IMT valve operation.
Test Electrical Connections	Use a multimeter to test the electrical connections for proper voltage and ground.
Consider ECM/PCM Issues	Investigate the Engine Control Module (ECM) or Powertrain Control Module (PCM) for potential faults.