P0023
Powertrain"B" Camshaft Position - Actuator Circuit (Bank 2)
This is an electrical fault in the circuit that controls the exhaust camshaft timing actuator on bank 2. The ECU sends a signal to the oil control valve to advance or retard the cam, and when that signal or the circuit feeding it goes wrong, P0023 lands. For you that usually means a warning light, a slightly grumpy engine, and a job that starts cheap (oil or wiring) but can climb if the actuator itself has packed up.
ⓘ Information only. This page provides general educational information about fault code P0023. We do not assess the urgency or safety implications of any specific fault. That requires in-person diagnosis by a qualified mechanic. Full terms.
Recommended next steps
Whether a fault is urgent, drivable, or routine depends entirely on the cause on a specific vehicle, and that can only be determined by a qualified mechanic with diagnostic equipment. If a warning light is illuminated, the most reliable next step is professional diagnosis.
What does P0023 mean?
P0023 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: "B" Camshaft Position - Actuator Circuit (Bank 2).
This is a standardised OBD-II code. The technical definition is the same regardless of the make or model of vehicle, although specific causes and symptoms can vary between vehicles.
Symptoms commonly associated with this code
Symptoms that drivers often report alongside this code. Not all may apply to every case:
- • Engine warning light on the dash, sometimes the first and only sign anything's wrong
- • Rough idle or a hesitation when you put your foot down
- • Down on power, the engine feels flat compared to how it used to pull
- • Fuel economy creeping up, more noticeable on a longer run
- • Occasional hard starting, especially first thing on a cold morning
- • Stalling now and then, often as you lift off and slow down
Possible causes
Causes commonly associated with P0023, listed in approximate order of typical investigation. The actual cause on a specific vehicle can only be confirmed by professional diagnosis.
- 1. Sticking or failed oil control valve (the VVT solenoid) on bank 2. This is the usual suspect and often it's just clogged with old oil sludge
- 2. Wiring or connector trouble at the solenoid, corroded pins, a chafed loom, or a connector that's worked loose with heat and vibration
- 3. The camshaft actuator (phaser) itself worn or seized, which is the pricier end of the scale
- 4. Low oil level or the wrong viscosity oil, the VVT system needs proper oil pressure to do anything
- 5. Old, sludged-up oil restricting the tiny passages the solenoid relies on
- 6. Timing chain stretch or a worn tensioner throwing the cam timing out enough to trigger it
- 7. A failed ECM, which is rare and only worth considering once everything else checks out
How mechanics typically diagnose
A typical diagnostic sequence used by mechanics, provided here for educational reference only. Diagnostic work should be performed by a qualified mechanic with the appropriate tools and training.
- 1. Pull the codes and look at the freeze-frame data. Knowing whether the fault logged hot, cold, idling or under load tells you a lot before you touch a spanner
- 2. Check the oil. Level, condition, and that it's the correct grade for the engine. Black, thin or low oil will starve the VVT system and is the cheapest thing to rule out
- 3. Inspect the wiring and connector at the oil control valve. Look for green corrosion on the pins, a damaged loom near the head, and give the plug a wiggle to check it's seating properly
- 4. Measure the resistance of the oil control valve solenoid with a multimeter and compare it to the manufacturer's spec. An open or out-of-range coil points straight at the valve
- 5. Check continuity on the wiring back to the ECM for a break or a short to earth or power
- 6. Run the manufacturer's pinpoint test for the VVT circuit if the basics check out, since these systems vary a fair bit between makes
Common questions about P0023
If I clear the code, does it stay gone or come straight back? +
If it's a real circuit fault, it'll come back, usually within a few drive cycles and sometimes the same trip. Clearing it is fine for checking whether a wiggled connector or topped-up oil has actually solved it, but it won't fix a sticking solenoid or chafed wiring. If the light reappears, treat it as a genuine fault rather than a glitch and start working through the causes.
What's the risk if I just leave it? +
In the short term you'll live with rough running and worse economy. The bigger worry is that the cam timing isn't being controlled properly, so the engine can run with the timing in the wrong position. On some engines that means accelerated wear, and if the underlying issue is oil starvation it can point to bigger lubrication problems brewing. It won't grenade overnight, but it's not something to ignore for months.
How quickly do I need to sort this? +
It's not a roadside emergency, you can drive carefully to a garage. Book it in within a week or two rather than letting it run for ages. If the car drops into limp mode, runs very rough, or you start hearing rattles from the front of the engine, stop driving it and get it looked at properly, because that combination can mean timing chain or oil pressure trouble.
Is it the actuator part itself or just the wiring? +
More often it's the oil control valve or the wiring and connector feeding it, both of which are cheaper and easier than the actuator. The phaser inside the engine is the expensive failure, so any decent diagnosis confirms the solenoid is good and the wiring is clean before anyone quotes you for stripping the front of the engine. Insist they prove it's the actuator before paying for that job.
Information only, not professional advice
The information on this page is provided for general guidance and educational purposes only. It is not a substitute for diagnosis or repair advice from a qualified mechanic. Always verify any fault before paying for repairs. carfaultcodes.co.uk accepts no liability for decisions made based on this information. Full terms →