P0025
Powertrain"B" Camshaft Position - Timing Over-Retarded (Bank 2)
The exhaust cam on bank 2 is sitting more retarded than the ECU asked it to, so the variable valve timing isn't where it should be on that cylinder bank. Bank 2 is the side of the engine that doesn't have cylinder number one, so this is really a V6 or V8 fault most of the time. For you as the owner it usually shows up as a warning light with some rough running, and the most common reason behind it is dirty or wrong oil starving the timing solenoid rather than anything broken.
ⓘ Information only. This page provides general educational information about fault code P0025. 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 P0025 mean?
P0025 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: "B" Camshaft Position - Timing Over-Retarded (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, sometimes with no other obvious change
- • Lumpy or uneven idle, worse from cold
- • Noticeable loss of power, the engine feels flat when you ask for it
- • Harder starting on a cold morning
- • Fuel economy creeps up and emissions can rise with it
- • A misfire-type stumble if the timing is well out
Possible causes
Causes commonly associated with P0025, listed in approximate order of typical investigation. The actual cause on a specific vehicle can only be confirmed by professional diagnosis.
- 1. Old, contaminated, or wrong-grade oil clogging the bank 2 VVT solenoid. This is far and away the most common cause and the cheapest to put right
- 2. Sticking or failed VVT solenoid on the bank 2 exhaust cam, often gummed up from neglected oil changes
- 3. Worn or hydraulically locked camshaft phaser that can't move to the commanded position
- 4. Damaged or corroded wiring and connectors at the solenoid or cam sensor, letting the signal drop out
- 5. Faulty bank 2 camshaft position sensor feeding the ECU duff readings
- 6. Stretched timing chain causing the cam to lag the crank, common on higher-mileage chain-driven engines
- 7. Low oil level or weak oil pressure so the actuator never gets enough flow to move
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. Check the oil first. Dipstick level, condition, and that it's the correct viscosity for the engine. Black, thin, overdue oil is the single biggest cause here, and an oil and filter change clears a good number of these before you spend on parts
- 2. Read the codes properly and note anything alongside it. P0025 with P0021 or P0020 points at bank 2 timing as a group; misfire codes change the picture
- 3. Inspect the wiring and connector to the bank 2 VVT solenoid and cam sensor for corrosion, chafing, or a loose pin. Wiggle-test while watching live data
- 4. Measure the solenoid resistance with a multimeter, you're looking for roughly 7 to 12 ohms, and use the scan tool to command it open and shut to see if it actually moves
- 5. If oil, wiring, and solenoid all check out, look at the phaser itself for wear or seizure. On a chain engine, check chain stretch and tensioner condition at the same time
- 6. Confirm oil pressure is up to spec, because a weak pump or worn bearings will keep tripping this no matter what parts you fit
Common questions about P0025
Can I keep driving with a P0025 showing? +
Short local trips are usually fine if it's just the warning light and a bit of rough running. The car may feel down on power and use more fuel until it's sorted. If the light starts flashing or you hear knocking or rattling from the engine, stop and get it recovered, because a phaser or chain that lets go can wreck valves and pistons. Don't ignore it for weeks, the underlying cause tends to get worse, not better.
Is this going to fail the MOT? +
The code on its own isn't a fail. What the tester looks at is whether the engine management light is on when they check the dash. If the MIL is lit at the time of test, the car fails on the emissions and engine management side. Fix the cause, clear the code, and drive a few cycles so the light stays off before you book it in.
What sort of money am I looking at to fix it? +
Depends entirely on what's actually wrong. If it's the oil, an oil and filter change with the correct grade is the cheapest outcome by a mile, usually under £100 at an independent. A bank 2 VVT solenoid runs into the low hundreds fitted at an independent garage, more at a main dealer where access is awkward on a V engine. If it comes down to the phaser or a stretched timing chain, you're into mid to high hundreds and easily four figures on a V6 or V8 at a dealer. Get two or three quotes before you commit.
How do I work out which of these it is on my car? +
Start with the oil, because it's the likeliest culprit and the cheapest to rule in or out. If a fresh oil and filter change with the right viscosity clears it, you've found it. If the code comes straight back, get a scan tool on it and command the solenoid while watching live cam timing data. No movement points at the solenoid or the wiring to it, so check the connector before condemning the part. If the solenoid commands and moves but the timing still won't reach target, look harder at the phaser and chain. A bad cam sensor usually throws its own code and erratic readings rather than a steady over-retarded value.
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 →