P0021: "A" Camshaft Position — Timing Over-Advanced (Bank 2)

Severity: medium System: Ignition System Can drive: caution

Quick answer: P0021 is the Bank 2 counterpart of P0011: the "A" (intake) camshaft timing on Bank 2 is over-advanced or the variable valve timing (VVT) system isn’t responding. It only appears on engines with two banks. As an oil-driven system, the first suspects are dirty/old oil or a stuck VVT oil-control valve, then the cam phaser or sensor.

TL;DR

P0021 = cam timing over-advanced (Bank 2) / VVT fault. Severity: medium. Only on two-bank engines. Top causes: dirty oil or clogged VVT oil-control valve (55%), faulty phaser (25%), sensor/wiring (20%). Start with fresh oil + OCV cleaning.

Can I keep driving with P0021?

Yes, with caution.

IF the engine runs acceptably → drive short-term and start with an oil change. IF it idles very rough, stalls or lacks power → diagnose sooner.

Symptoms

Check engine light on
Rough idle
Reduced power
Worse fuel economy
Occasional stalling or hard start

Top causes (ranked by probability)

Likely cause	Probability	Notes
Dirty/old/low oil or clogged VVT oil-control valve	55%	Start here
Faulty Bank 2 cam phaser/actuator	25%
Camshaft sensor or wiring fault (Bank 2)	20%

What does P0021 mean?

Technical explanation

P0021 mirrors P0011 for Bank 2 (the bank without cylinder 1). The ECM detects actual cam phase more advanced than commanded. Because the VVT phaser is oil-actuated via the oil-control valve, contaminated/low oil and a clogged OCV dominate, then a worn phaser or sensor/wiring fault.

In simple terms

P0021 is the same valve-timing problem as P0011, but on the second side of the engine (Bank 2). As with P0011, dirty oil or a gummed-up control valve is usually to blame — start with an oil change and cleaning that valve.

How to diagnose P0021 (step by step)

Check oil level and condition. Change overdue/dirty oil with the correct grade first.
Clean/inspect the Bank 2 oil-control valve. Remove and clean the VVT solenoid; replace if clogged.
Scan for companion codes. P0011/P0024 alongside narrow the diagnosis.
Test OCV and actuator. Confirm the solenoid and phaser respond.
Inspect wiring/connector. Check the OCV and cam-sensor circuits on Bank 2.

Repair options & cost

Change oil/filter (correct grade)
Clean or replace the Bank 2 VVT oil-control valve
Replace the cam phaser/actuator if faulty
Repair sensor/wiring

DIY cost	$20–$250
Workshop cost	$120–$700
Repair time	30 min (oil/OCV) to 3+ hours (phaser)

Costs are local ballpark ranges and vary by region and vehicle.

Tools you’ll need

OBD-II scanner (BlueDriver / ANCEL)
Oil change kit
Basic socket set

Scan your car: recommended OBD-II scanners →

Vehicle-specific notes

Only engines with two banks (V6/V8/V) have a Bank 2.
Keep oil changes current — VVT depends on clean oil.
Often resolved by oil + OCV cleaning before the costlier phaser.

Common mistakes to avoid

Replacing the phaser before trying oil + OCV cleaning
Wrong oil viscosity
Working on the wrong bank
Ignoring oil-change intervals

Frequently asked questions

What is the difference between P0011 and P0021?

They are the same VVT/cam-timing fault on different banks: P0011 is Bank 1 and P0021 is Bank 2. P0021 only appears on engines with two banks.

Can an oil change fix P0021?

Often, yes. VVT is oil-driven, so fresh correct-grade oil plus cleaning the oil-control valve resolves many cases.

Is P0021 serious?

Medium severity — the car runs with degraded performance/economy. Start with oil and the OCV.

P0021 summary

Meaning	Cam timing over-advanced / VVT (Bank 2)
Severity	Medium
Safe to drive?	Yes, short-term
Top cause	Dirty oil / clogged OCV (55%)
DIY cost	$20–$250
Shop cost	$120–$700