How do I fix the engine code P0320?
The engine code P0320 signals an ignition/distributor engine speed input circuit malfunction. In plain terms, the engine control module isn’t getting a clean, trustworthy signal about engine speed from the crankshaft or distributor, and the signal path may be faulty.
In practice, this means a signal integrity problem that can stem from a faulty crankshaft or distributor sensor, damaged wiring or connectors, a problem in the ignition input circuit, or, less commonly, a failing engine control module. The exact cause depends on your vehicle’s make, model, and age, so a careful, systematic diagnostic approach is essential.
What P0320 Means
P0320 is an OBD-II diagnostic trouble code indicating an ignition/ distributor engine speed input circuit malfunction. The engine computer relies on a reliable reference signal to time spark events. If the signal is missing, erratic, or out of range, the PCM can set P0320 and may illuminate the check engine light. This code is often accompanied by related codes such as P0335 (Crankshaft Position Sensor) or P0316/P0330 (signal timing issues), which helps technicians pinpoint the fault area.
Diagnostic Steps
To identify the root cause, mechanics follow a structured diagnostic approach that starts with confirming the code and assessing related symptoms.
- Verify the code and review freeze-frame data with a scan tool to understand engine conditions when the code was stored.
- Check for related codes (such as P0335, P0325, or P0350) and symptoms like misfires, long cranks, or rough idle to narrow the fault domain.
- Inspect ignition wiring and connectors at the crank/distributor sensor and at the ignition coil input circuit for corrosion, loose pins, or damaged insulation.
- Test the power supply and ground paths for the PCM and the sensor circuits to ensure clean, stable voltage references.
- Test the crankshaft position sensor or distributor signal source (resistance, voltage output, and waveform if you have an oscilloscope). Look for unusual readings or a nonfunctional sensor.
- Check the timing system (if applicable) and inspect the reluctor ring, sensor mounting, and timing belt/chain for proper alignment and wear.
- Evaluate ignition coil(s) and coil harnesses for fault conditions in primary/secondary circuitry; swap or test coils if needed to rule out a faulty coil.
- Consider PCM/ECU fault hypotheses only after ruling out wiring, sensor, and coil issues; in rare cases, a reflash or replacement may be required.
After these steps, technicians typically re-check the system by clearing codes and performing a drive cycle to confirm the fault is resolved or to identify any new symptoms.
Common Fixes
Below are the most frequent repairs that address P0320. If multiple issues exist, several fixes may be required to restore proper function.
Sensor and signal issues
Faulty or failing sensors and weak signal paths are common culprits. Addressing these often restores proper engine speed input to the PCM.
- Replace a defective crankshaft position sensor or distributor sensor and ensure proper alignment and mounting.
- Repair or replace damaged sensor wiring and connectors; fix corrosion, loose pins, or broken wires.
- Repair or replace any damaged ignition input wiring to the PCM or coil packs; reseat or clean connector pins.
Once sensor and signal issues are addressed, the engine should supply a stable speed signal to the PCM, which helps prevent P0320 from returning.
Electrical wiring and grounds
Electrical faults outside the sensor itself can produce intermittent or degraded signals that trigger P0320.
- Repair damaged ground paths between the engine, battery, and PCM; clean and secure battery terminals and ground straps.
- Check fuses and relays related to ignition and PCM power; replace faulty fuses/relays as needed.
- Inspect the entire ignition and PCM harness for wear, chafing, or water intrusion; replace compromised harness segments.
Proper wiring and ground integrity helps ensure the PCM receives consistent, noise-free speed reference information.
ECU/PCM considerations
Infrequent cases, the engine control unit itself can misinterpret or fail to process the input signal even when the sensor and wiring are sound.
- Update or reflash the PCM software if a known fault is addressed by the manufacturer.
- Repair or replace a failing PCM in coordination with a professional technician, especially if wiring and sensors test normal but codes persist.
PCM-related fixes are generally pursued after all sensor and wiring issues have been thoroughly tested and ruled out.
Costs and Timelines
Costs for addressing P0320 vary widely based on the vehicle and the root cause. Diagnostic labor typically ranges from $100 to $200, plus parts. Parts costs can include sensor replacements ($20–$150 per sensor), coil packs ($60–$300 per coil or more for premium setups), wiring repairs ($50–$200 depending on extent), and possible PCM reflashes or replacement (several hundred dollars, depending on make and regional labor rates). A full repair, including parts and labor, can range from a few hundred to well over a thousand dollars in complex cases.
Timeline depends on the complexity of the fault. Sensor or wiring repairs can often be completed in a few hours, while ECU-related work may require more time for diagnostics, programming, and testing on a test drive.
When to Seek Professional Help
Because P0320 involves the engine’s speed reference signal and its path to the PCM, professional diagnosis is strongly recommended if you’re not comfortable with electrical testing or if the fault persists after basic checks. A qualified technician can perform advanced voltage and waveform tests, inspect timing components, and verify software or PCM integrity.
- Persistent check engine light with intermittent misfires or rough idle.
- Failure to locate a clear, repeatable fault after basic inspections.
- Vehicle safety or drivability concerns tied to engine timing or stalling.
Summary
P0320 denotes an ignition/distributor engine speed input circuit malfunction, typically caused by sensor faults, wiring issues, or, less commonly, PCM problems. A structured diagnostic approach—checking sensors, wiring and grounds, power supply to the PCM, and the timing components—helps pinpoint the fault. Common fixes include replacing faulty sensors, repairing wiring, ensuring solid ground paths, and addressing any PCM-related issues if required. Costs and timelines vary, but a methodical diagnostic with targeted repairs often resolves the code and restores reliable engine performance.
How serious is the P0320 code?
Because OBD-II scanner error code P0320 problem is considered a fault in the electrical circuit, there may not be many performance issues. You'll simply see the malfunction indicator light and your OBD-II scanner will read code P0320. However, a fault in either the CKP or CMP could prevent your engine from starting.
How do I fix error code P0320?
Look for corrosion, loose wires or cracked connectors and replace as necessary. Finally, the sensors themselves may have an internal short. Visually inspect the CKP and CMP sensors, as well as any other ignition sensors, and test the voltage to ensure they're working effectively.
How do you fix the ignition distributor engine speed input circuit?
How To Correct P0320 Ignition/Distributor Engine Speed Input Circuit Malfunction
- Diagnose and repair any existing low battery voltage settings.
- Replace the crankshaft position sensor.
- Replace whichever crankshaft position sensor wiring or connector that is broken, shorted, or corroded.
- Replace the camshaft position sensor.
What is the engine speed input malfunction on a Kia P0320?
DTC P0320 stands for “Ignition/Distributor Engine Speed Input Circuit.” It's logged when the PCM detects that the CKP sensor doesn't transmit signals after the CMP sensor. A defective CKP sensor, a bad CMP sensor, a damaged crankshaft (or camshaft sensor tone wheel), and a malfunctioning PCM can trigger the error code.
