OBD-II trouble code
P0006: Fuel Shutoff Valve "A" Control Circuit Low
Voltage on the shutoff valve's control leg is being pulled down when it should not be. On an energise-to-run design that leaves the valve permanently open — the engine runs, and the key can no longer stop it.
Quick facts
- System
- Powertrain
- Category
- Fuel & Air
- Severity
- High severity
- Drivable
- No — stop driving until repaired
- Repair cost range
- $110 – $1,700
- DIY difficulty
- Advanced DIY
What does P0006 mean?
P0006 means the module measured less voltage on the fuel shutoff valve's control circuit than the state it commanded should produce. On the low-side switched circuits these valves normally use, that means something other than the module is completing the path to ground — a wire touching the engine or a bracket, a flooded connector tracking between pins, or a shorted turn inside the solenoid itself.
What makes this member of the block different from an open circuit is that the module has not lost control neutrally. It has lost control in one specific direction. It can still see the circuit, but it can no longer turn it off, because the ground path exists whether the driver commands it or not. On an energise-to-run valve that means the fuel path is held open permanently, and the practical consequence is a vehicle whose ignition key has stopped being a stop switch. The engine starts, runs, drives, and then keeps running when the key comes out. That is a safety problem rather than a performance one, and it is the reason this code is rated the way it is despite the car feeling perfectly normal to drive.
A permanently grounded output also runs into the module's own defences, and this is worth understanding because it explains a confusing symptom pattern. Low-side drivers monitor the current they are sinking and shut themselves down when it exceeds a limit, then attempt to re-enable on the next key cycle. From the driver's seat that looks like a fault that comes and goes for no reason: the light goes out, everything is fine for a day, then it is back. Every one of those cycles is a driver being overloaded and cooled. Repeatedly clearing the code and carrying on is the documented route by which a sixty-dollar wiring fault turns into a control module replacement.
There is one partition test that belongs at the top of the plan because it splits the problem in half in a single step. Unplug the solenoid and see what the module reports. If the code converts to an open-circuit fault, the short is inside the solenoid winding and the harness is fine. If it stays low with nothing connected, the ground is in the wiring or in the module, and no new solenoid will help. That one measurement decides whether you are buying a part or tracing a wire.
The environment this circuit lives in also shapes where to look. The shutoff solenoid is bolted to the injection pump body — a component that is hot, oily, and vibrating continuously. Insulation there does not usually wear through against a bracket the way a loom does behind a headlight. It hardens with heat, then fractures at a flex point and lays bare copper against the pump casting, which is grounded by definition. So the inspection to run is a close look at the last few inches of lead where it leaves the connector, not a general hunt along the harness.
Common causes
- Control wire chafed or cracked through to the injection pump casting, which is a permanent ground by construction
- Shorted turn inside the solenoid winding, grounding the circuit internally
- Water, salt or diesel-soaked debris in the solenoid connector tracking between the control pin and a ground pin
- Heat-hardened insulation on the pump-mounted pigtail that has fractured rather than abraded
- Control wire pinched under a bracket, clamp or intake component refitted after previous work
- Failed low-side driver in the engine control module that is stuck pulling the circuit down
- Aftermarket wiring or an anti-theft fuel cut spliced into the shutoff circuit
- Corroded module connector with the control pin bridged to an adjacent ground cavity
Symptoms
- Engine continues to run after the ignition is switched off and the key removed
- Engine starts normally and drives with no performance complaint while the light is on
- Check engine light that clears itself and returns over successive key cycles as the module's driver trips and resets
- Fuel cut function unavailable, so the engine cannot be stopped by normal means
- Blown fuse in the fuel system circuit, replaced and blown again
- Intermittent stalling on vehicles where the module reacts to the short by disabling the output
- Burning insulation smell near the injection pump on a hot engine
- Additional unrelated circuit codes from the same section of loom
Diagnostic steps
- 1.Treat a vehicle that will not shut off with the key as unroadworthy and arrange recovery rather than a test drive.
- 2.Unplug the solenoid and read the codes again. If the fault converts to an open circuit the short is inside the coil; if it stays low, the problem is in the harness or the module.
- 3.Measure resistance from the solenoid's control terminal to the pump body. A low reading with the connector off confirms an internally grounded winding.
- 4.With the connector off at both ends, measure resistance from the control wire to chassis ground. Anything but an open indicates the wire is grounding somewhere along its run.
- 5.Inspect the last few inches of lead where it leaves the connector at the pump, flexing it while watching the meter. Heat-cracked insulation hides under a lead that looks intact.
- 6.Look for a wire pinched under a bracket, clamp or intake component, especially if the fault appeared shortly after unrelated work in the engine bay.
- 7.Check the solenoid connector for salt, moisture or oil-soaked debris bridging pins, and clean rather than replace if that is what you find.
- 8.Trace any aftermarket fuel cut, immobiliser bypass or auxiliary wiring spliced into this circuit.
- 9.Avoid repeatedly clearing and re-testing while the short is live, since each cycle overloads the module's driver.
- 10.After repair, confirm the engine both runs and shuts off cleanly on the key, then re-check for the code after several full drive cycles.
Repair cost
$110 – $1,700
Diagnosis is $110 to $200 and is a better buy here than on most codes, because the unplug-the-solenoid test partitions the fault in one step. A harness or pigtail repair where the wire has grounded against the pump is $130 to $450. A shutoff solenoid with an internally shorted winding is $40 to $160 for the part plus $80 to $300 labour on a mechanical pump. Where the shutoff function is integrated into a common-rail high-pressure pump the figure rises to $500 to $1,700. Add $400 to $1,200 for module replacement and programming if the driver has been destroyed, which is the outcome repeated code-clearing tends to produce.
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DIY vs shop
This is an advanced DIY job. It typically requires specialty tools, scan-tool access, lifting equipment, or careful sequencing to avoid causing new failures. Plan for extended downtime and have a backup vehicle. Most owners are better served by a shop that has done this repair before.