# P0018: Crankshaft Position - Camshaft Position Correlation (Bank 2 Sensor A) **Verdict:** Drive to a shop this week Camshaft timing - Generic OBD-II code, applies to all gasoline cars and light trucks sold in the US since 1996. - **Typical cost:** $150-$3,500 - **Urgency:** This week - **Most likely:** Worn timing chain, guide or tensioner - **DIY?:** Shop job ## Quick answer P0018 means the engine computer sees the bank 2 intake camshaft out of step with the crankshaft. It only appears on V6, V8 and other engines with two cylinder banks. Timing chain stretch is the classic cause, and on engines with a separate chain for each bank, the bank 2 chain, guide or tensioner is often to blame. ## What does P0018 mean? On a V-type or flat engine, each cylinder bank has its own camshafts, all driven from the crankshaft by one or more timing chains or a belt. Some designs use a primary chain from the crank plus a secondary chain for each bank. The engine computer reads a crank sensor and a cam sensor for each camshaft, and it knows where each cam signal should fall against the crank signal. P0018 sets when the bank 2 "A" cam signal sits outside its expected window. Under SAE J2012, "A" means intake, left or front, so on most engines this is the bank 2 intake cam. Bank 2 is the side of the engine opposite cylinder 1; service information shows which side that is. Most makers run the check at idle with the phasers parked, and many need two trips. P0016 is the matching bank 1 check. ## What are the symptoms of P0018? - Check engine light on - Rattle from the front of the engine at a cold start - Rough idle or vibration at stops - Slower starting than usual - Reduced power, especially pulling away or climbing hills ## What causes P0018? Ranked from most to least likely. Check them in this order: the cheap, common causes first. 1. **Stretched timing chains, worn guides or tensioners** (most common). As chains wear they lengthen, and the camshafts fall behind the crankshaft. On V engines with one long chain or a shared primary chain, stretch usually sets codes on both banks, such as P0016 with P0018. High mileage and long oil change intervals are typical. A rattle at cold start is often the first clue. 2. **Worn bank 2 secondary chain, guide or tensioner** (common). Engines that use a separate chain for each bank can wear one side faster, so P0018 may set while bank 1 codes stay clear. A worn bank 2 tensioner or a broken guide lets that chain slap and lose its tension. The bank 2 timing parts are usually reached only after removing the engine front cover. 3. **Bank 2 intake phaser stuck, or an oil problem** (less common). A bank 2 intake cam phaser that cannot park at its rest position, because of low or dirty oil, sludge or a failed lock pin, can push the cam outside the correlation window. A cam timing code for that side, such as P0021, often sets too. Checking the oil and commanding the bank 2 solenoid comes first. 4. **Faulty bank 2 intake cam sensor or tone wheel** (less common). A weak bank 2 intake cam sensor signal, a damaged tone wheel or a poor connection can make the timing look off even when the chain is fine. On many V engines that sensor sits at the back or top of the bank 2 head. A circuit code such as P0345 alongside P0018 points toward the sensor. 5. **Bank 2 cam timed wrong after a repair** (rare). If the code appeared after a timing chain, head gasket or chain-driven water pump job, the bank 2 cam may have been installed a tooth off. On some transverse V6 engines, timing the rear bank is awkward and the marks are easy to misread. Checking marks and correlation values before more driving is cheap insurance against valve damage. ## How do you diagnose P0018? 1. Read all codes and note whether bank 1 correlation codes (P0016, P0017) are also set or only bank 2. 2. Check oil level and condition, and ask about any recent timing or head work. 3. On a scan tool, view bank 2 intake cam correlation or deviation values at warm idle and compare them with bank 1. 4. Scope the crank and bank 2 cam signals together to measure how far off the timing is. 5. Remove the front cover to inspect chains, guides, tensioners and timing marks for the affected bank. ## How do you fix P0018, and what does it cost? | Fix | Typical cost | What it involves | | --- | --- | --- | | Replace bank 2 intake cam position sensor | $150-$450 | Rear-bank sensors on transverse engines take longer to reach. | | Re-time a chain or belt installed incorrectly | $400-$1,200 | For codes that appear right after timing work, if no valves were damaged. | | Replace timing chain set (V6 or V8) | $1,500-$3,500 | Chains, guides and tensioners; most shops replace the full set on both banks. | Full price breakdowns: [timing chain replacement cost](/cost/timing-chain-replacement), [camshaft position sensor replacement cost](/cost/camshaft-position-sensor-replacement). ## Is it safe to drive with P0018? > **Drive to a shop this week.** Drive only as needed and have it diagnosed within a few days. A worn chain on a V engine can jump or break, and many V6 and V8 engines are interference designs where that damages valves. Stop driving if a loud rattle appears or the engine suddenly runs rough. ## Will P0018 fail an emissions test? P0018 turns on the check engine light, so the vehicle fails an OBD-II emissions inspection in most states. Even if the car drives fine, testers read the stored code straight from the computer. After a chain or sensor repair, the cleared readiness monitors need several days of normal driving to finish, so plan the test for after they show ready. ## After the repair: clearing P0018 Once the repair is complete, clear the codes and look at bank 2 cam correlation values on a scan tool; they should match bank 1 closely and sit within the maker's range. Any cold-start rattle should be gone. Drive several trips that include cold starts and long idles, then confirm no pending code has returned. ## How to prevent P0018 - Follow the severe-service oil interval if you tow, idle a lot or mostly drive short trips. - Use the exact oil specification for your V6 or V8, since chain tensioners depend on it. - Have timing chain noise checked early, before guides break and pieces reach the oil pan. - When chain parts on one bank are replaced, ask whether the other bank is worn too. - Keep the oil level full, because tensioners rely on oil pressure to keep chains tight. ## P0018 by make | Make | What to know | | --- | --- | | GM | GM 3.6L V6 engines in models such as the Chevrolet Traverse, GMC Acadia and Cadillac CTS from roughly 2008 to 2011 often set P0018 with other correlation codes from timing chain stretch. | ## Codes often seen with P0018 - [P0016](/codes/p0016): Crankshaft Position - Camshaft Position Correlation (Bank 1 Sensor A) - [P0019](/codes/p0019): Crankshaft Position - Camshaft Position Correlation (Bank 2 Sensor B) - [P0017](/codes/p0017): Crankshaft Position - Camshaft Position Correlation (Bank 1 Sensor B) - [P0021](/codes/p0021): "A" Camshaft Position - Timing Over-Advanced or System Performance (Bank 2) - [P0345](/codes/p0345): Camshaft Position Sensor "A" Circuit (Bank 2) - [P0335](/codes/p0335): Crankshaft Position Sensor "A" Circuit ## Frequently asked questions ### Can I drive with a P0018 code? You can usually drive a short distance with P0018, but get it checked within a few days. Timing chain stretch is the most common cause, and a chain that keeps wearing can jump teeth or break. On many V6 and V8 engines that causes valve damage and a far bigger repair bill. ### Where is bank 2 for P0018? Bank 2 is the side of a V or flat engine that does not contain cylinder 1. Which side that is depends on the maker and on how the engine sits in the car. Service information or a repair guide shows the cylinder numbering, so check it before working on any bank 2 parts. ### Why do I have P0018 but not P0016? P0018 without P0016 points to something that affects only bank 2. Common examples are a worn bank 2 secondary chain, guide or tensioner, a sticking bank 2 intake phaser, or a bank 2 cam sensor problem. A single long chain or a primary chain problem would usually set codes on both banks. ### How much does it cost to fix P0018? Most P0018 repairs cost $150 to $3,500 at an independent shop. A bank 2 cam sensor runs $150 to $450, and re-timing a chain or belt that was installed wrong costs $400 to $1,200. A full V6 or V8 timing chain set usually costs $1,500 to $3,500. ### Can a bad cam sensor cause P0018? Yes, a failing bank 2 intake cam sensor can cause P0018, although chain wear is the more common cause. A weak or erratic signal makes the cam look out of place. A circuit code such as P0345 alongside P0018, or a bad pattern on a scope, points to the sensor. ### Can I fix P0018 myself? Most owners can read codes, check the oil and, if it is reachable, replace the bank 2 cam sensor. Diagnosing chain stretch needs a scan tool that reads correlation values, or a scope. Replacing timing chains on a V engine takes many hours and special tools, so it is usually a shop job. ### Does P0018 mean the timing chain is bad? P0018 often means the timing chain or its guides and tensioners are worn, but not always. A sticking cam phaser, a faulty cam sensor or timing set wrong after a repair can cause it too. A shop should confirm with correlation data or a scope before quoting a chain job. ### Should I replace all timing chains if P0018 sets? On most V engines, shops replace the full timing set on both banks rather than only the bank 2 parts. The chains and guides wear together, and much of the labor is shared. Replacing everything at once costs more now but avoids paying for the same teardown twice. ### Can oil changes prevent P0018? Regular oil changes with the right oil are the best protection against P0018. Dirty or low oil speeds wear of the chains, the guides and the oil-fed tensioners that keep chains tight. Many chain stretch cases trace back to long oil change intervals or engines that ran low on oil. ### Will P0018 go away by itself? P0018 rarely goes away for good on its own, because chain wear does not reverse. The light may turn off for a few trips if the timing drifts back into range, but the code usually returns. If it comes back, have the timing measured before the chain wears further. ## Sources - [SAE J2012: Diagnostic Trouble Code Definitions](https://www.sae.org/standards/content/j2012_201812/) - [EPA: On-Board Diagnostics (OBD)](https://www.epa.gov/state-and-local-transportation/vehicle-emissions-board-diagnostics-obd) ## Other camshaft timing codes - [P0010 "A" Camshaft Position Actuator Circuit (Bank 1)](https://diagxcar.com/codes/p0010) - [P0011 "A" Camshaft Position - Timing Over-Advanced or System Performance (Bank 1)](https://diagxcar.com/codes/p0011) - [P0012 "A" Camshaft Position - Timing Over-Retarded (Bank 1)](https://diagxcar.com/codes/p0012) - [P0013 "B" Camshaft Position Actuator Circuit (Bank 1)](https://diagxcar.com/codes/p0013) - [P0014 "B" Camshaft Position - Timing Over-Advanced or System Performance (Bank 1)](https://diagxcar.com/codes/p0014) - [P0015 "B" Camshaft Position - Timing Over-Retarded (Bank 1)](https://diagxcar.com/codes/p0015) - [P0016 Crankshaft Position - Camshaft Position Correlation (Bank 1 Sensor A)](https://diagxcar.com/codes/p0016) - [P0017 Crankshaft Position - Camshaft Position Correlation (Bank 1 Sensor B)](https://diagxcar.com/codes/p0017) - [P0019 Crankshaft Position - Camshaft Position Correlation (Bank 2 Sensor B)](https://diagxcar.com/codes/p0019) - [P0021 "A" Camshaft Position - Timing Over-Advanced or System Performance (Bank 2)](https://diagxcar.com/codes/p0021) - [P0345 Camshaft Position Sensor "A" Circuit (Bank 2)](https://diagxcar.com/codes/p0345) ## Symptoms - [Why is my car idling rough?](https://diagxcar.com/symptoms/rough-idle) - [Why does my car lose power when accelerating?](https://diagxcar.com/symptoms/car-loses-power-when-accelerating) - [Why does my car crank but not start?](https://diagxcar.com/symptoms/car-cranks-but-wont-start) ## Repair costs - [Timing chain replacement cost](https://diagxcar.com/cost/timing-chain-replacement): $1,200-$3,500 - [Camshaft position sensor replacement cost](https://diagxcar.com/cost/camshaft-position-sensor-replacement): $120-$350 --- Source page: https://diagxcar.com/codes/p0018 Updated: 2026-11-03 General information, not a substitute for a qualified mechanic.