P0339
Crankshaft Position Sensor A Circuit IntermittentP0339 is a generic OBD-II powertrain diagnostic trouble code: Crankshaft Position Sensor A Circuit Intermittent. It is logged by the engine control unit when the ckp/cmp monitor detects that a specific fault threshold has been exceeded — typically resulting in the malfunction-indicator lamp (MIL / check-engine light) being illuminated.
What P0339 means
P0339 is triggered when the PCM observes an intermittent or erratic signal from Crankshaft Position Sensor "A" — the signal is present but drops out unpredictably rather than failing in a fixed direction. Because the fault is not continuous, it is one of the more difficult CKP codes to diagnose: the problem may disappear entirely when the vehicle is cold or at rest, only returning under vibration, heat, or a specific RPM range.
The most common hardware culprits are a damaged or corroded reluctor wheel (bent, missing, or heavily pitted teeth create gaps in the pulse train), a cracked sensor body that shifts its air gap as it expands with heat, and harness sections that flex with engine movement and open momentarily under vibration. Oil contamination of the sensor connector is another frequent cause, as petroleum degrades the wire insulation and causes transient shorts. The signature diagnostic technique is the wiggle test — flex the harness by hand while monitoring the CKP signal on an oscilloscope at idle; any signal dropout or spike during harness movement pinpoints the fault location. An oscilloscope is strongly preferred over a simple multimeter because the intermittent pulses occur at high frequency and are invisible to a slow-update meter.
Common causes
Most-frequently reported root causes when P0339 is logged.
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1
Damaged reluctor wheel — bent, missing, or severely corroded teeth creating gaps in the pulse train
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2
Cracked or thermally stressed sensor body shifting air gap as engine heats up
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3
Harness chafing or flexion fracture causing momentary open circuits as the engine moves
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4
Oil or coolant contamination degrading connector insulation and causing transient shorts
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5
Loose or corroded sensor connector with intermittent pin contact
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6
Sludge or debris bridging reluctor teeth and disrupting the magnetic field
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7
Failing Hall-effect element inside the sensor that drops out under heat or vibration
Symptoms drivers notice
How to diagnose P0339
A typical diagnostic flow when this code is present.
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1
Scan all codes and note freeze-frame data; check whether any companion CKP or CMP codes are present that could indicate a broader timing issue
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2
Perform a thorough visual inspection of the harness from sensor to PCM, paying close attention to sections that pass near exhaust manifolds, pulleys, or engine mounts where flexion or heat damage is common
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3
Connect an oscilloscope to the CKP signal wire and run the engine at idle — look for any missing pulses, amplitude dropouts, or noise spikes in the waveform pattern
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4
With the oscilloscope still connected, perform a wiggle test: flex the harness in sections and jostle the connector while watching for signal interruptions that identify the fault location
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5
Inspect the reluctor wheel through the sensor port using a flashlight for bent, missing, or debris-coated teeth; rotate the engine by hand if necessary to view the full wheel
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6
Check sensor resistance and connector pin retention; replace the sensor if resistance is out of specification or the body shows cracking
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7
Clear codes and perform an extended road test over varied RPM and load conditions, with oscilloscope data logging if possible, to confirm the repair
Related powertrain codes
- P000A — A Camshaft Position Slow Response Bank 1
- P000B — B Camshaft Position Slow Response Bank 1
- P000C — A Camshaft Position Slow Response Bank 2
- P000D — B Camshaft Position Slow Response Bank 2
- P0010 — A Camshaft Position Actuator Circuit (Bank 1)
- P0011 — A Camshaft Position - Timing Over-Advanced or System Performance (Bank 1)
Frequently asked questions
Why is P0339 harder to diagnose than P0337 or P0338?
Because the fault is intermittent, it may not be present when you connect the test equipment. Static resistance or voltage checks will pass, giving a false all-clear. An oscilloscope capturing the live waveform during a wiggle test or a hot restart is the most reliable way to catch the dropout.
Can a damaged reluctor wheel cause P0339?
Yes, and it is one of the more common causes. A bent or missing tooth on the reluctor wheel creates a repeating gap in the pulse train at a specific crankshaft angle. This shows up clearly on an oscilloscope as a periodic missing pulse rather than a random dropout.
Does P0339 always cause a stall?
Not always. Short dropouts may only cause a brief stumble or misfire. Extended dropouts — especially if the PCM loses position sync — can trigger a stall or prevent restart. Severity depends on how long and how often the signal is interrupted.
Should I replace the CKP sensor first on P0339?
It is reasonable as a first step given the relatively low cost, but inspect the harness and connector carefully first. If the sensor connector is corroded or the harness shows damage near a heat or flex point, repairing the wiring may resolve the fault without sensor replacement.
Disabling P0339 in software
RaceTune can permanently disable P0339 — and any other OBD-II diagnostic trouble code — on every ECU family we support. The monitor is disabled inside the ECU itself, so the fault stops being logged: the warning light stays off and the engine never enters limp mode for this code. The change is tied to your exact software version.
Software modifications affect emissions compliance and are not road-legal in many jurisdictions. RaceTune service files are intended for motorsport, off-road, and export use.
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