P0323
Ignition/Distributor Engine Speed Input Circuit IntermittentP0323 is a generic OBD-II powertrain diagnostic trouble code: Ignition/Distributor Engine Speed Input Circuit Intermittent. It is logged by the engine control unit when the powertrain monitor detects that a specific fault threshold has been exceeded — typically resulting in the malfunction-indicator lamp (MIL / check-engine light) being illuminated.
What P0323 means
P0323 — "Ignition/Distributor Engine Speed Input Circuit Intermittent" — is stored when the PCM detects a signal from the crankshaft position sensor or distributor speed pickup that drops out, spikes, or drops below the minimum pulse threshold intermittently during normal engine operation. Unlike P0320, which flags a continuous or range-based fault, P0323 specifically indicates that the fault is non-continuous — the signal returns to normal between failure events, making it harder to reproduce on demand.
The PCM relies on a steady train of pulses from the engine speed input to manage ignition timing and fuel injection with cycle-by-cycle precision. Even brief signal dropouts cause the PCM to lose track of crank position, resulting in misfires, rough idle, or momentary stalls. In some calibrations, a persistent intermittent pattern can eventually trigger limp mode or disable fuel injection temporarily until the signal is reacquired. P0323 can be a precursor to a complete P0320 failure as a sensor or connector degrades further.
Because the fault is intermittent, reproducing it often requires monitoring live data during an extended drive cycle or under conditions that stress the connection — such as engine heat-soak, vibration, or cold starts. Connector and wiring inspection is the highest-yield first step, as moisture intrusion and loose pins account for the majority of intermittent circuit faults on CKP sensor circuits.
Common causes
Most-frequently reported root causes when P0323 is logged.
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1
Loose, corroded, or intermittently contacting connector pin at the CKP sensor or distributor pickup.
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2
Chafed or pinched wiring that makes intermittent contact under vibration or thermal cycling.
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3
Moisture or condensation in the sensor housing or connector boot causing intermittent short circuits.
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4
Crankshaft position sensor with a degrading internal coil or reluctor-ring pickup beginning to fail.
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5
Weak battery or charging system providing unstable 5V reference voltage under load.
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6
PCM input circuit with intermittent solder joint or pin corrosion at the engine speed input.
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7
Reluctor ring with a developing crack or slightly damaged tooth producing periodic signal dropout.
Symptoms drivers notice
How to diagnose P0323
A typical diagnostic flow when this code is present.
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1
Retrieve all stored and pending codes; note the freeze frame data, particularly engine temperature and load at the time of the fault.
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2
Inspect the CKP sensor connector and wiring harness carefully for loose pins, moisture, corrosion, or chafing — wiggling connectors while monitoring live RPM data can expose intermittent opens.
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3
Measure the 5V reference and ground circuit voltages at the sensor connector; test under load (engine running) as well as with ignition on to catch voltage sags.
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4
Monitor live engine speed (RPM) PID on a scan tool during an extended drive, paying attention to any sudden drops to zero or spikes that correlate with drivability symptoms.
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5
Use an oscilloscope on the signal wire during the drive cycle — signal dropouts will appear as missing pulses in the otherwise regular waveform.
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6
Inspect the reluctor ring for cracked, missing, or damaged teeth that would cause periodic pulse dropout.
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7
Replace the CKP sensor if the wiring and connector are confirmed sound and signal dropout is reproducible; retest with an extended drive cycle to confirm the code does not return.
Related powertrain codes
Frequently asked questions
What is the difference between P0320 and P0323?
P0320 indicates a continuous or persistent engine speed input circuit malfunction — the signal is absent or out of range in a sustained way. P0323 indicates the fault is intermittent — the signal returns to normal between dropout events. P0323 is often an early warning that the same components responsible for P0320 are beginning to fail.
Why is P0323 so hard to diagnose?
Because the fault only occurs under specific conditions — often involving engine heat, vibration, or moisture — it may not be present during a workshop inspection. Extended road-test monitoring with a live data scanner or oscilloscope, ideally under the conditions that trigger the symptom, is usually required to catch the dropout in real time.
Can P0323 cause a no-start?
Yes, particularly after engine heat-soak when the sensor or connector is at its most thermally stressed. If the dropout occurs during cranking before the engine fires, the PCM may withhold fuel and spark. Most drivers experience intermittent hard-start or stalling rather than a complete no-start until the condition worsens.
Should I replace the crankshaft sensor or the wiring first?
Inspect and repair wiring and connectors first — loose or corroded pins and moisture ingress are the most common cause of intermittent circuit faults and are cheaper to fix. If wiring is in good condition and the dropout is confirmed by oscilloscope, replace the sensor. Replacing the sensor without checking the wiring often fails to resolve the fault.
Disabling P0323 in software
RaceTune can permanently disable P0323 — 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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