P0018 Code: Crankshaft/Camshaft Position Correlation (Bank 2 Sensor A)
The bank 2 intake cam is out of step with the crankshaft on a V or boxer engine; chain wear leads the list.
Stop driving
If there is any rattle, whine or clatter from the timing covers, or the engine stumbles, stop and arrange a tow. Without noise, drive gently and only to the workshop; no road trips and no trailer towing with this code stored.
At a glance
Severity: High
- Meaning
- Crankshaft/Camshaft Position Correlation (Bank 2 Sensor A)
- System
- Fuel & Air Metering · Powertrain
- Safe to drive?
- With caution
- Typical repair cost
- $90–$7,000
- DIY difficulty
- Professional only
P0018 can only appear on engines with two cylinder banks, such as V6, V8 and boxer engines. The PCM checks where the bank 2 intake cam signal falls relative to the crankshaft signal while the phaser is parked, and stores the code when the gap exceeds its learned limit. Bank 2 is the bank that does not contain cylinder 1. Many V engines use a primary chain from the crankshaft plus a separate secondary chain or drive for each head, so the code pattern tells you a lot: bank 2 codes on their own point to parts only bank 2 has, while P0016 and P0018 together, often with P0008, point to the shared primary chain. As with any correlation fault, a chain that has lost tension can skip, and on most V engines that means expensive valve damage.
How to read P0018
- P Powertrain
- 0 Generic (SAE)
- 0 Fuel/air & emissions (aux.)
- 18 Specific fault
Symptoms
- Check engine light, often with P0008 or P0016 also stored
- Rattle at cold start that fades once oil pressure builds
- Reduced power and noticeably worse fuel economy
- Rough running or misfire codes limited to bank 2 cylinders
- Long cranking, or stalling soon after startup in advanced cases
Possible causes
Ranked by how often each cause is behind this code (editorial estimate).
- Primary timing chain stretched (bank 1 correlation codes usually set too)
- Bank 2 secondary chain, guide or tensioner worn
- Bank 2 intake phaser not locking in its base position
- Oil level, oil quality or hot oil pressure too low to keep the tensioners pumped up
- Bank 2 intake cam sensor, its wiring or tone wheel at fault
- Bank 2 camshaft timed incorrectly after a head gasket or chain repair
Diagnosis step by step
Map all four correlation values
In live data, note the cam/crank deviation for intake and exhaust on both banks. All four drifting the same way means the primary chain; only the bank 2 cams drifting means the bank 2 drive; only the bank 2 intake points to that cam's phaser, sensor or tone wheel.
Tools: OBD-II scanner
Identify bank 2 and find its sensor
Find cylinder 1 in service information; the opposite bank is bank 2. On a transverse V6, bank 2 may face the firewall or the radiator depending on the make, which decides how much has to come off to reach its cam sensor.
Tools: Flashlight
Swap intake cam sensors between banks
Where both intake cam sensors are the same part, swap them and clear the codes. If the fault moves to P0016, the sensor is bad; if P0018 stays put, the problem is mechanical or in the bank 2 wiring.
Tools: Screwdriver, OBD-II scanner
Check oil level and hot oil pressure
Chain tensioners on V engines are oil-fed, and low level or low hot-idle pressure lets a secondary chain slap. Correct the oil and confirm pressure with a mechanical gauge before tearing down the front of the engine.
Tools: Torque wrench, Flashlight
Scope the bank 2 intake cam against the crank
Comparing the bank 2 intake cam edges with the crank pattern on a two-channel scope puts a number on the error and shows whether it is steady, meaning stretch or a timing error, or jumping around, meaning something loose.
Inspect the timing drive
If the numbers point to the chain, remove the front cover, inspect the primary and bank 2 chains, guides and tensioners, and check the timing marks on both heads. On many V6 engines it makes sense to replace every chain and guide in one go.
Tools: Torque wrench, Flashlight
Where the parts are
- 1Ignition coil
- 2Spark plug
- 3Fuel injector
- 4Camshaft sensor
- 5Crankshaft sensor
- 6Engine computer (ECM)
- 7Intake manifold
Repair options & costs
| Repair | DIY? | Estimated cost |
|---|---|---|
| Replace bank 2 intake camshaft sensor | Yes | $90–$280 |
| Repair bank 2 cam sensor wiring | No | $100–$300 |
| Replace bank 2 secondary chain, guides and tensioner | No | $1,200–$2,400 |
| Complete V6 timing chain set with all guides and tensioners | No | $2,000–$4,000 |
| Engine repair after a skipped chain | No | $3,500–$7,000 |
Rough US estimates for parts and labor; shop rates vary by region. Not a quote.
Notes by brand
Chevrolet
The 3.6 V6 in the Traverse, Equinox, Camaro and Malibu is well known for timing chain stretch, often linked to long oil change intervals. It typically logs P0008 along with several of P0016 through P0019, and the fix is usually the complete set of chains, guides and tensioners.
GMC
Acadia and Terrain models with the 3.6 V6 share its chain stretch problem. When P0018 appears with P0008 or P0016, have the cam/crank deviation readings checked before the chain becomes noisy, since the repair costs far less before the chain skips.
Ford
The first-generation 3.5 EcoBoost V6 in the F-150 is known for timing chain stretch and cam phaser rattle at startup, which can bring up cam/crank correlation codes on either bank. Updated phasers and chains are the usual remedy.
Emissions / smog test impact
Will fail
P0018 keeps the check engine light on, so an OBD-II emissions inspection will fail. A chain repair on a V engine also resets the readiness monitors, so plan about a week of normal driving between the repair and the retest.
Frequently asked questions
Which side of my engine is bank 2?
Bank 2 is the bank that doesn't contain cylinder 1. Manufacturers number cylinders differently, so check service information or the firing order label under the hood rather than assuming it's the driver's or the passenger's side.
Why only a bank 2 code if the chain is stretched?
Many V engines drive each head with its own secondary chain, and one bank's drive can wear faster than the other's. The PCM also judges each cam separately, so one bank can cross the limit first even when both are drifting.
Is it worth replacing only the bank 2 chain?
Sometimes, if inspection shows the primary chain and the other bank are in good shape. Labor to reach bank 2 overlaps heavily with a full chain job, though, so many shops recommend doing all chains and guides together.
Could a new aftermarket cam sensor have caused P0018?
Yes, if the code appeared right after a sensor was replaced. Some cheap sensors switch at a slightly different point on the tone wheel, which the PCM reads as a timing offset. Refit a quality sensor before chasing the chain.
Sources
- SAE J2012 – Diagnostic Trouble Code Definitions
- ISO 15031-6 – Road vehicles, diagnostic trouble code definitions (EOBD)
- Manufacturer public service information (cross-checked)
- NHTSA Complaints API
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