P1345: How to Diagnose & Fix — Crankshaft Position - Camshaft Position Correlation
2 vehicles · 2 makes · $600-$1,500 repair
How to diagnose and fix P1345: most-reported vehicles
Ranked by owner reports. Each card gives the symptoms, how to confirm the cause, the fix, parts and sources for that vehicle.
BMW 2 Series · 2014–2025
Every US 2 Series engine (N20, N26, N55, B46, B48, B58) is direct injected, so no fuel washes over the back of the intake valves. Oil vapor from the crankcase ventilation system and EGR-side carbon bake onto the valve stems and ports, progressively choking airflow and disturbing the intake charge. Owners report the classic pattern: rough cold idle, hesitation on tip-in and between roughly 1,500-2,500 rpm, hard hot restarts, and eventually cylinder-specific misfire codes that do not resolve with coils and plugs. Deposits are usually meaningful by 60,000-80,000 miles and severe by 100,000, and are worse on short-trip and city-driven cars. It is frequently misdiagnosed and treated with repeated coil/injector replacement before anyone pulls the intake manifold and looks.
Common Symptoms
- Rough idle, especially when cold
- Hesitation on throttle tip-in between 1500-2500 rpm
- Hard restart when hot
- Cylinder-specific misfires that return after new coils and plugs
- Reduced power and worse fuel economy
- Rough running under light load
How to Fix
Remove the intake manifold and walnut-blast (crushed walnut media) the intake ports and valve backs — this is the BMW-recognized cleaning method and does not require pulling the head. Replace the intake manifold gasket and any brittle vacuum lines at the same time. Address the cause as well: replace a failing PCV/crankcase vent valve if it is passing oil vapor, and shorten oil change intervals. Chemical intake cleaners and fuel additives can slow accumulation but will not remove baked-on deposits. Plan on repeating the service roughly every 60,000-100,000 miles.
Sources for this issue (3)
Buick Roadmaster · 1994–1996
The 1994-1996 LT1 uses a camshaft-driven 'Optispark' optical distributor mounted at the front of the engine, low on the timing cover directly behind the water pump. Its optical disc and low-voltage electronics are extremely sensitive to moisture and oil. Any coolant weep from the water pump above it, a failed crankcase vent hose, engine-bay washing, or driving through water can foul the optical sensor and cause misfires. Because it sits behind the water pump, replacement is labor-intensive. This is the single most notorious LT1 (and therefore Roadmaster) driveability failure. The early design vented poorly; B-bodies, including the Roadmaster, got the vacuum-vented unit for 1994, a year before the Corvette and F-body.
Common Symptoms
- Engine stumble, hesitation, or surge under acceleration
- Audible misfire and rough idle
- Excessive vibration
- Hard starting or no-start when wet
- Check engine light / misfire codes
How to Fix
Replace the Optispark with an AC Delco (vented) unit, and because the water pump has to come off to access it, replace the water pump at the same time. Ensure the distributor vent hoses are correctly routed and clear so condensation can escape. Rule out spark plug wires and plugs first, as those often mimic Optispark failure.
Sources for this issue (2)
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P1345 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does P1345 mean?
P1345 stands for "Crankshaft Position - Camshaft Position Correlation." A manufacturer-specific powertrain code; on General Motors vehicles (Chevrolet, GMC, Buick, Cadillac, Pontiac, Saturn, Isuzu) it is set when the signals from the crankshaft position sensor and camshaft position sensor fall out of their expected relationship - commonly cited as roughly 1.5 to 2 percent of crankshaft rotation out of sync. The PCM needs this correlation to time spark and fuel correctly. Symptoms include a check engine light, rough idle or misfire, hard starting, and stalling. On older GM V6/V8 engines this frequently points to a worn timing chain, a real mechanical repair that should not be ignored. Other makes (including Honda, Suzuki and some imports) assign P1345 a different meaning, so confirm the definition for your make before diagnosing.
What are the most common causes of P1345?
The most common causes of P1345 are: Stretched or worn timing chain / failed chain tensioner or guides (very common on higher-mileage GM engines), Faulty camshaft position sensor, Faulty crankshaft position sensor or damaged reluctor wheel, Loose or improperly seated sensor at its mounting, or wrong sensor installed, Damaged wiring, connector corrosion, or shielding fault on either sensor circuit, Incorrect ignition/cam timing after recent timing component service, Crankshaft position variation relearn not performed after PCM or sensor replacement. The specific cause varies by vehicle.
How much does it cost to fix P1345?
Repair costs for P1345 range from $600 to $1,500, depending on the vehicle and root cause.
Which vehicles are affected by P1345?
Au7o has documented P1345 across 2 vehicle models from 2 manufacturers: BMW, Buick.
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Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.