P0006 Code: Fuel Shut-off Valve "A" Control Circuit Low

The P0006 code is a highly specific engine code that alerts the driver to a problem with one of the engine's high-pressure fuel valves. Though considered to be a rare diagnostic code, P0006 can be found in passenger vehicles and light trucks manufactured after 1996. It also more commonly appears in vehicles with diesel engines.

Read on to find out more about code P0006, including what causes it, its symptoms, and recommended repairs.

What Does Code P0006 Mean?

Code P0006 is a diagnostic trouble code (DTC) that stands for “Fuel Shut-off Valve “A” Control Circuit Low.” It means the vehicle's onboard computer is having trouble communicating with the engine's fuel shut-off valve.

Located next to the fuel supply rail, the shut-off valve cuts the fuel supply to the fuel pump and is controlled by the powertrain control module (PCM). If the latter detects a signal from the valve that's lower than the expected voltage, it switches on the check engine light and stores the P0006 code.

Many gasoline vehicles don't have a fuel shutoff solenoid, so this code won't be seen on most vehicles unless they have a stop-start system—but not all start-stop vehicles have one.

Cummins diesel engines have a fuel shutoff solenoid (see Illustration below).

If the vehicle is equipped with a fuel shutoff solenoid, it will be situated on the injector pump to move a lever. This solenoid, if malfunctioning, can prevent the vehicle from starting by blocking fuel flow.

Mercedes uses a vacuum diaphragm for this purpose.

What Causes Code P0006?

Code P0006 can often be traced back to a broken fuel shut-off valve. It may also be due to shorted or damaged connectors or wiring linking the valve to the engine control module (ECM). Sometimes, the PCM might store a P0006 code by mistake due to a software glitch, although this very rarely occurs.

• Broken fuel shut-off valve
• Broken wires and connectors
• PCM issues

Broken Fuel Shut-off Valve

Damage or defects in any of the internal components of the shut-off valve may cause it to send inaccurate readings to the PCM.

Broken Wires and Connectors

Damaged, corroded, or worn wires and connectors can interrupt the signal from the fuel shut-off valve, which the PCM might misinterpret as invalid and trigger the code.

PCM Issues

The PCM itself may also malfunction due to corrupted or outdated software and log P0006 or other engine codes as a result.

What are the Symptoms of Code P0006?

There are a handful of symptoms associated with code P0006, but the check engine light is likely the first sign you'll notice. The engine may also continue to run even if the ignition is switched off, which is known as "dieseling." The engine might also fail to start or stall when running.

Other known symptoms include reduced engine performance and poor fuel mileage.

It should be noted that not all of these symptoms may show up in the event the code P0006 is stored in your vehicle. In rare cases, no signs would appear at all.

• Illuminated check engine light
• Dieseling
• Ignition problems
• Engine stalling

Illuminated Check Engine Light

The check engine light automatically switches on whenever the PCM stores an engine code, so it's often the first—and sometimes the only—sign of a P0006 code.

Dieseling

If the fuel shut-off valve is no longer working properly, fuel may flow uninterrupted and leak into the combustion chamber. And if the air is still hot enough inside the chamber, it may ignite the fuel and cause the engine to continue to run even with the ignition switched off.

Ignition Problems

The engine may also struggle to start or, in some cases, refuse to start at all. This is because there isn't enough fuel pressure to reliably trigger a spark in the combustion chamber.

Engine Stalling

Lack of adequate pressure can lead to an imbalanced fuel combustion, causing the engine to stall or stumble when idling.

How to Diagnose Code P0006

Diagnosing the exact cause of a P0006 can prove difficult, but it is possible, provided you have the tools and the time. Some of the general steps you can take include the following:

Verify and Analyze the Code

If you have an OBD-II scan tool, connect it to your vehicle and run a diagnostic scan. Verify if code P0006 or other diagnostic codes are under the active codes list.

Inspect the Fuel Shut-off Valve

Look for visible signs of corrosion or damage on the valve body. Use a multimeter to check for voltage and resistance and compare them with the manufacturer's specifications.

Inspect the Wiring

Look for cut, bent, or frayed wires and bent or corroded metal terminals. Check if the contacts are tightened properly.

Check the PCM

If you think the PCM is what's causing P0006 to appear, take the module to your dealership or repair shop for advanced diagnostic tests.

How to Fix Code P0006

Fixing a code P0006 will depend on what's causing it and how serious it is. Some of the common solutions related to this code are:

Replace the Fuel Shut-off Valve

If the fuel shut-off valve is damaged or defective, it needs to be replaced. Make sure the replacement valve is OE-compatible to ensure the code doesn't reappear.

Repair or Replace the Wiring

Tighten connectors if they are loose and clean any corrosion on metal contacts using contact cleaner spray. However, if the wires are worn or damaged, they must be replaced.

Reprogram or Replace the PCM

Outdated or corrupted PCM software has to be professionally updated or reprogrammed. If the code persists or the PCM has suffered severe damage, it will have to be replaced as well.

Other Codes Related to P0006

P0006 is one of a few engine codes assigned to the fuel shut-off valve. These codes include:

P0005

This diagnostic code means the PCM has detected an open circuit with the fuel shut-off valve.

P0007

Similar to the P0006 code, this DTC indicates a higher-than-normal voltage coming from the fuel shut-off valve.