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Code P0660: Meaning, Symptoms + Diagnosis


P0660 is a somewhat common OBDII code. It is generic, so it has the same meaning for any vehicle manufactured since 1996. It occurs most frequently in vehicles manufactured by GM, Toyota and Chrysler.

Roughly speaking, it means there is a problem with the bank on one side of the intake manifold valve timing control circuit. The most common causes of this code are a defective wiring harness to/from the intake trim valve, a defective PCM, or a defective intake manifold trim valve control circuit.

P0660 Definition: Intake Manifold Tuning Valve Control Circuit Open (Bank 1)

P0660 Fault code definition

Here you have the meaning of the definition of P0660 divided into its three different parts.

Intake manifold trim valve control circuit

The intake manifold tuning valve control system is responsible for redirecting air into the intake manifold

Relieves air pressure on the opposite side of the intake manifold. Or, you can channel the air through a completely different duct for power/efficiency purposes.


An open implies that two points of an electrical circuit are externally disconnected. In this case, the two points in question are the PCM and the intake manifold trim valve control circuit.

The wiring between these two parts of your vehicle can run through a CAN bus system, which is a union of cables. Getting a schematic of your car or truck (exact model year and engine combination is essential) can make it easier to determine the cause of P0660. Before doing so, you should do a quick visual inspection for any obvious problems (more on this below).

Any of the vehicle modules can detect this problem. Some examples of different modules are body control, transmission, ABS, and traction control. If there is a problem in the PCM, the other modules may still report P0660.

Bank 1

Bank 1 is the part of your vehicle with the first cylinder. You don’t have to worry about this if you have an inline-four or inline-six engine.

P0660 Symptoms

There are usually symptoms associated with P0660. Here are the most common ones.

  • check engine light
  • Decreased power at the upper end of the RPM range
  • Reduced fuel consumption
  • Rough/unknown idle
  • Difficulty starting

Engine power decay is more likely to occur at the higher end of the RPM range. It can occur at any engine speed. You may only notice the check engine light. It just depends on the vehicle in question.

P0660 Causes and diagnosis

P0660 Diagnostic

Here are the most common causes of P0660 and a good order to check them at home.

1. Check the manufacturer’s communications

Manufacturers send communications through “technical service bulletins,” commonly referred to as TSBs. Although this site does not maintain a database of them, they are easy to find online

If you click the link above, it will take you to the NHTSA website in a new window. Look here for your exact year and model of vehicle. If there is a TSB related to the intake manifold adjusting valve, it gives you a good place to start your diagnosis with a known failure point.

2. Inspect the wiring harness

Check the wiring connector on the bank on one side of the intake manifold tuning valve control circuit.

Examine where it connects to the harness. Make sure there is no visible damage to it or the pins inside. If there is damage, you may need to repair it or replace it. If there is corrosion, use a good electrical contact cleaner to clean it.

Now that you have verified that the harness connector looks good, examine the wiring leading from the intake manifold control valve as far as you can. Look for damaged, frayed, or burned cables. If there is, replace the wiring in question

Check that the ground wire is solid and free of corrosion where it bolts to the body, engine, or frame. Then, pass a temporary ground to the intake manifold timing control valve. If the problem is fixed, you will need to fix the OEM ground wire.

3. Defective CAN bus

The CAN bus is responsible for taking the information from the different sensors and sending it to the modules that need it (including the PCM)

If the wiring harness seems fine until it reaches the CAN bus system, its pins will need to be inspected, which is getting into the weeds for most shady mechanics.

A mechanic could use a specialized scanner to determine precisely where in the wiring system the wiring harness is open and causing P0660. You could also check the continuity of the circuits.

4. Other causes

  • Bad PCM/ECM – Although the PCM is not usually the problem in most codes. If everything has been checked with the wiring, replacing or resetting the PCM may clear the P0660. Have a mechanic take a look at the vehicle before replacing the PCM
  • Faulty Intake Manifold Adjusting Valve – P0660 indicates a wiring problem with the intake manifold adjusting valve. But, if your wiring fails internally, it will throw the code. It’s not very high on the probability scale.


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