P0026
- Powertrain
- Generic (SAE)
- Emissions
Diagnose soon
Intake cam phasing that will not respond costs power, economy and emissions performance and can idle roughly, but it is not an immediate mechanical hazard. It becomes serious when the underlying cause is low oil pressure or heavy sludge, both of which are damaging the rest of the engine at the same time.
- Safe to drive
- Usually safe to drive short-term. Stop if oil pressure is low, the engine knocks, or it idles roughly enough to stumble.
Intake Valve Control Solenoid Circuit Range/Performance (Bank 1)
The engine computer detected that the bank 1 intake valve control solenoid is not performing the way it should — the circuit passed the module's basic open and short checks, but commanding the solenoid does not produce the response the module expects. That is a performance complaint about the solenoid and its oil circuit, not proof the solenoid is bad and not proof the wiring is good.
This is a range/performance code rather than an open or short code. The ECM commands the bank 1 intake oil control solenoid to a duty cycle and evaluates the result — either the resulting change in measured intake camshaft angle, or on some strategies the solenoid current versus the commanded duty. When the response is too slow, too small, absent, or inconsistent while the circuit itself passes its electrical checks, P0026 sets. Passing those checks only rules out a hard open or short: a high-resistance joint, a corroded terminal or a partly seated connector can still be the cause. Because the solenoid is only a valve in an oil circuit, the same symptom is also produced by a blocked screen, varnished feed passages, insufficient oil pressure, or a phaser that will not respond to correct oil delivery.
How the car detected itThe module runs the check under calibrated enable conditions — engine running, oil temperature above a threshold (measured or modelled, since many engines infer it from coolant temperature and run time), stable rpm and load. It commands a solenoid duty step and measures the actual response against an expected response map within a settling time. Failure to meet the expected response through the confirmation period sets the code. Manufacturers implement this differently: some evaluate cam angle response, some evaluate solenoid current or the driver's feedback voltage against the commanded duty. Thresholds are calibrated per engine, not generic.
A trouble code records what a control module measured. It does not identify which part failed. Test before replacing anything.
- Safe to drive
- Usually safe to drive short-term. Stop if oil pressure is low, the engine knocks, or it idles roughly enough to stumble.
- Urgency
- Diagnose soon
- Will it pass emissions
- No
- If ignored
- Reduced mid-range power and fuel economy continue, and the vehicle will not pass an emissions inspection. If sludge or low oil pressure is behind it, the same restriction is starving chain tensioners and bearings, and that damage accumulates quietly. Persistent rough idle also pushes unburnt fuel into the catalytic converter.
- Check engine light
- Solid
- Clearing the light
- A completed drive cycle is normally required before the monitor re-runs and the light can clear.
These are the causes this code can have. For the order to work through them in, see what to check first.
| # | Cause | How often | Component |
|---|---|---|---|
| 1 | Oil control valve mechanically stuck | Very common | — |
| 2 | Sludge or debris in oil passages | Common | — |
| 3 | Low oil pressure or wrong oil viscosity | Common | — |
Ordering reflects how often each cause is responsible in general, not a probability for your vehicle. Confirm by testing.
In order. Each of these is cheaper or faster than what follows it, and each one can make the rest unnecessary.
Oil level, condition and specified grade
The solenoid is a valve in an oil circuit. Low, sludged or wrong-viscosity oil produces this exact detection with a perfectly good solenoid, and ruling it out costs nothing.
Oil change interval history
This code appears far more often on engines with extended or missed oil services than on well-maintained ones. Varnish in the screen and feed drillings is the common thread.
Whether the solenoid connector is secure and dry
A partially seated or oil-contaminated connector gives intermittent control that reads as poor performance rather than a hard circuit fault — and it will still pass the module's open and short checks.
Freeze frame — coolant temperature, and oil temperature where the vehicle reports it, when it set
A code that only sets cold points at flow restriction and viscosity; one that sets hot points at the solenoid, the phaser, or oil pressure. Not every engine reports oil temperature, so coolant temperature and run time may be all you have.
Any companion VVT codes on bank 2 or on the exhaust cam
Multiple VVT codes at once shift the diagnosis toward oil supply and condition rather than one failed solenoid.
Check oil level, condition and viscosity
Tools Dipstick, shop light
Level on flat ground, inspect the dipstick and filler cap for sludge and varnish, and confirm the grade in the sump matches the manufacturer's specification. Service overdue oil before further testing, because a restricted circuit invalidates every measurement that follows.
ExpectedFull, clean, correct specified grade
Measure oil pressure with a mechanical gauge
Tools Mechanical oil pressure gauge and adapter, service information
Read pressure at idle and raised rpm with the engine at full operating temperature. The scan-tool pressure value and the dash lamp are not sufficient here. Specified pressures are vehicle-specific.
Confirm the solenoid circuit is genuinely healthy
Tools Digital multimeter, back-probe leads, service information
Do not skip this because the code says 'performance'. Verify the control and supply circuits under load: winding resistance at the solenoid, supply voltage present with the key on, and voltage drop on the ground and control side while the solenoid is actually being commanded. A high-resistance connection passes the module's open and short checks and still produces this exact detection. Resistance specifications vary by vehicle.
ExpectedSupply near system voltage, no significant voltage drop under load, winding within the vehicle's specification
Command the solenoid and watch cam angle respond
Tools Scan tool with bidirectional controls and live data graphing
At warm idle, sweep the bank 1 intake phaser with bidirectional control while graphing desired and actual cam angle. No movement, sluggish movement, or overshoot each point at a different part of the circuit. Idle quality should change audibly when the phaser moves. Confirm the engine's specified park value before judging the resting angle.
ExpectedPrompt full-range movement with actual tracking desired within the manufacturer's allowed error
Scope the solenoid current waveform
Tools Lab scope, low-amp current clamp
A low-amp current clamp on the control wire shows whether the driver is producing a clean PWM current ramp and whether the solenoid is actually stroking. A flat or erratic current trace separates an electrical fault from a mechanically stuck spool.
ExpectedClean, repeatable current ramps matching the commanded duty cycle
Remove and bench-test the solenoid
Tools Hand tools, 12 V bench supply, borescope, shop light
Inspect the inlet screen for varnish, sludge and metal debris. Stroke the spool with a 12 V bench supply — it must move fully and return under spring pressure without hesitation. Inspect the feed passage in the head or cover while the valve is out.
ExpectedClean screen, free-moving spool with full return, clear feed passage
Assess the phaser and mechanical timing if the solenoid is good
Tools Cam locking tools, service information
A known-good solenoid delivering oil at correct pressure into a phaser that still will not move points at the phaser itself or at the chain. Verify timing against the manufacturer's reference position or with the specified locking tools before condemning the phaser.
| Repair | Only after you confirm | Typical cost | Who |
|---|---|---|---|
| Oil and filter change with the correct specified viscosity | Oil found degraded, low, sludged or the wrong grade, and solenoid response returns to normal afterwards | $60–$180 | DIY |
| Bank 1 intake oil control solenoid and screen replacement | Spool found sticking or the screen blocked on bench inspection, with oil pressure verified adequate and the circuit verified healthy under load | $140–$420 | DIY |
| Connector or wiring repair at the solenoid | Voltage drop under load, corrosion, oil intrusion or a spread terminal found, and the current waveform cleans up after repair | $90–$320 | DIY |
| VVT oil feed passage cleaning or engine sludge remediation | Varnish or debris found in the feed passage or the sump, with a known-good solenoid still failing to move the phaser | $200–$1,200 | Hard |
| Bank 1 intake camshaft phaser replacement | Solenoid, circuit, oil pressure and feed passage all verified good, but the phaser still does not respond to command | $650–$2,200 | Shop |
| Oil pump or pickup screen service | Mechanical gauge reads below the manufacturer's specification at operating temperature with correct oil in the sump | $700–$2,600 | Shop |
Bank 1 solenoid access is usually easier than bank 2 on a V engine, which is why the low end here is lower — but on a transverse engine with the intake manifold in the way, labour can still triple. Budget $90 to $180 for diagnosis, and expect a shop to insist on fresh correct-grade oil before diagnosing, which is reasonable rather than an upsell.
- Assuming a range/performance code proves the wiring is fine. It only means the circuit passed the module's open and short checks — a high-resistance connection, a corroded terminal or a partly seated connector can still be the cause, so confirm supply, ground and voltage drop under load before condemning the solenoid or the hydraulics.
- Replacing the solenoid without ever looking at its screen, then reusing the same contaminated oil circuit.
- Skipping the mechanical oil pressure test because the oil light is off. That lamp typically warns only at pressures far below what a phaser needs.
- Confusing this with P0011. P0026 targets the solenoid's response; P0011 targets the resulting cam timing. They overlap and often appear together, but they are not the same test.
- Assuming bank 1 is a fixed side of the engine. Bank 1 is the bank containing cylinder 1, and its location varies by make and engine.
- Oil Control Valve
- Camshaft Position Actuator
- Engine Oil
- Definition
- Generic code set (SAE J2012 / ISO 15031-6) via the OBDexopen database, dedicated to the public domain under CC0-1.0.
- Diagnostic guidance
- Written and reviewed in-house. See our editorial policy.
- Review status
- Reviewed
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