P001B
A Camshaft Profile Control Circuit Low Bank 1P001B is a generic OBD-II powertrain diagnostic trouble code: A Camshaft Profile Control Circuit Low Bank 1. It is logged by the engine control unit when the ckp/cmp monitor detects that a specific fault threshold has been exceeded — typically resulting in the malfunction-indicator lamp (MIL / check-engine light) being illuminated.
What P001B means
P001B — A Camshaft Profile Control Circuit Low (Bank 1) — is an electrical fault code indicating that the engine control module (ECM) has detected a voltage lower than expected in the control circuit for the intake ("A") camshaft profile switching actuator on Bank 1. Where P001A identifies an open circuit (no current path at all), P001B specifically identifies a low-voltage or short-to-ground condition: the circuit is completing but the signal voltage measured by the ECM is below the minimum threshold for a valid "high" or "commanded on" state. This typically results from a wire shorted to ground, a connector with a grounded pin, or an actuator coil that is partially short-circuited to the actuator housing. As with P001A, the profile-switching system (e.g. VTEC, two-stage lift) is inoperative and the engine is locked into its default low-lift cam profile. The ECM may also protect itself or the circuit by limiting current once it detects the abnormal low-voltage condition, which means the actuator will not be energised even if commanded. The code is flagged as medium severity but should be addressed promptly, as short-circuit conditions left unresolved can damage wiring insulation, connectors, and in extreme cases the ECM output driver.
Common causes
Most-frequently reported root causes when P001B is logged.
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1
Wire in the actuator control circuit shorted to ground (chafed insulation contacting chassis or engine)
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2
Corroded or water-damaged connector creating a low-resistance path to ground
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3
Internally short-circuited camshaft profile actuator solenoid coil
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4
Insufficient or contaminated engine oil causing hydraulic binding that loads the actuator electrically
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5
Incorrect or neglected oil service resulting in sludge restricting actuator oil feed passages
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6
ECM output driver failure causing the circuit to read incorrectly low
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7
Poor or missing ground at an engine block ground strap creating reference voltage errors
Symptoms drivers notice
How to diagnose P001B
A typical diagnostic flow when this code is present.
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1
Connect a scan tool, retrieve all stored codes and freeze-frame data; check whether the code appeared under specific RPM or load conditions (freeze frame RPM often coincides with the normal profile-switch threshold)
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2
Visually inspect the actuator wiring harness for any sign of chafing against hot, sharp, or vibrating surfaces; pay special attention to areas near exhaust manifolds and engine mounts
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3
With the ignition on (engine off), measure the voltage at the actuator control wire; a low-voltage short will show significantly less than the expected supply or reference voltage
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4
Perform a wire-to-ground resistance test on the actuator control wire back to the ECM connector; a resistance below ~10 kΩ to ground indicates a short
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5
Disconnect the actuator and retest the circuit — if the short disappears, the actuator coil is shorted internally; if it persists, the short is in the harness
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6
Check and service engine oil if overdue; verify oil pressure is within specification as inadequate oil can mechanically load the actuator and contribute to electrical anomalies
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7
Inspect ECM connector for moisture ingress or corrosion; verify ECM ground circuit integrity with a voltage-drop test before suspecting an internal ECM fault
Related powertrain codes
- P000A — A Camshaft Position Slow Response Bank 1
- P000B — B Camshaft Position Slow Response Bank 1
- P000C — A Camshaft Position Slow Response Bank 2
- P000D — B Camshaft Position Slow Response Bank 2
- P0010 — A Camshaft Position Actuator Circuit (Bank 1)
- P0011 — A Camshaft Position - Timing Over-Advanced or System Performance (Bank 1)
Frequently asked questions
What is the difference between P001A and P001B?
P001A is an open circuit fault — the circuit has no complete path and no current flows. P001B is a low-voltage (short-to-ground) fault — the circuit is connected but voltage is being pulled below the valid threshold by an unintended ground path. Diagnosis starts the same way but diverges: P001A uses continuity tests while P001B uses resistance-to-ground tests.
Can low oil pressure cause P001B?
Not directly — P001B is a circuit voltage fault, not a hydraulic one. However, if contaminated or insufficient oil causes the actuator mechanism to physically stick or bind, the increased current draw as the ECM tries to force the actuator can trip over-current protection and present as a low-voltage condition. Always service the oil as part of diagnosis.
How serious is P001B compared to P001A?
Both produce similar drivability effects (locked in low-lift cam profile), but P001B carries slightly higher urgency because a short-to-ground left unresolved can overheat wiring insulation and potentially damage the ECM output driver. P001A (open circuit) has no current flowing so hardware damage from the fault itself is minimal.
Will the car rev normally with P001B?
The engine will rev through the full RPM range, but it will feel noticeably weaker above the RPM threshold where the profile switch normally engages (typically 3,000–5,500 rpm depending on manufacturer). Below that threshold, normal low-lift power is available.
Disabling P001B in software
RaceTune can permanently disable P001B — and any other OBD-II diagnostic trouble code — on every ECU family we support. The monitor is disabled inside the ECU itself, so the fault stops being logged: the warning light stays off and the engine never enters limp mode for this code. The change is tied to your exact software version.
ECU families we can disable P001B on
We hold the DaVinci A2L disable definitions for these families, so the exact P001B path and mask addresses are mapped. verified marks a confirmed disable definition. We support many more — upload your file and our identifier will match it automatically.
- Bosch MG1CP002 verified
Software modifications affect emissions compliance and are not road-legal in many jurisdictions. RaceTune service files are intended for motorsport, off-road, and export use.
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