P0320 on Mazda: How to Diagnose & Fix
Ignition/Distributor Engine Speed Input Circuit Malfunction
2 Mazda models · 2 documented issues · $40-$550 repair
P0320 on Mazda by model: symptoms, diagnosis and fix
The 2.5L KL-DE V6 uses a cam-driven distributor with an internal O-ring/oil seal at the base and a shaft bushing. As the seal hardens with age, engine oil weeps up the shaft and pools inside the distributor cap, fouling the cap and rotor and shorting the ignition. On higher-mileage cars the shaft bushing also wears, allowing shaft wobble that both worsens the leak and disturbs the pickup signal. The result is a rough-running, misfiring, hard-starting or stalling V6 that many owners chase before finding the source. This is a well-known KL-engine quirk shared with the MX-6 and Ford Probe GT.
Common Symptoms
- Oil pooled inside the distributor cap
- Rough idle and random misfire
- Hard starting, especially when damp
- Intermittent stalling
- Hesitation under acceleration
How to Fix
First-line fix is replacing the cheap base O-ring/seal (a few dollars) plus a fresh cap and rotor and cleaning the shaft, which cures most cases; applying a little sealer at the cap on reinstall helps. If the distributor shaft has visible play/wobble, the whole distributor must be replaced (reman ~$150-300 plus labor). Keeping oil out of the cap also prolongs plug-wire and coil life.
Sources for this issue (4)
First-generation Proteges (and 1.5L second-gen cars) use a camshaft-driven distributor that houses the ignition pickup. With age these distributors suffer internal bearing wear and moisture intrusion past the seal, which corrodes the pickup and shaft. The result is a car that runs fine cold but stalls once hot and refuses to restart until it cools, or a sudden loss of spark and a crank-no-start. Documented cases include a 1990 Protege that ran ~10 minutes then abruptly stalled until cold (fixed by a dealer distributor replacement) and a 1.8L DOHC no-start where new coil, wires, cap and rotor did not cure it until the distributor was replaced.
Common Symptoms
- stalls when engine is hot
- no-start until engine cools
- no spark / crank-no-start
- rough running or misfire
- intermittent dying while driving
How to Fix
Confirm loss of spark, then replace the complete distributor assembly (the internal pickup/bearing is not reliably serviceable on a worn unit). Reinstall carefully - the rotor can seat in more than one position, so mark distributor-to-block orientation and rotor direction before removal to preserve base timing. Replace cap, rotor, wires and check the seal while in there.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- BP02-18-200A / T2T53171 complete ignition distributorOEMBP02-18-200A / T2T53171
Complete distributor branch for a matching 1990-1991 Protege 1.8L distributor ID Fitment/availability: The inspected listing title names 1990-1991 Mazda Protege and BP0218200A/T2T53171/BP02-18-200A. It showed $173.47, six available and B…
- T2T53171B / T2T53071B complete ignition distributorOEMT2T53171B / T2T53071B
Confirm SOHC/DOHC configuration and the distributor ID
- AIP DT2T603 complete electronic ignition distributorOEMAIP DT2T603 / T2T60371 / BP1A-18-200
Complete distributor branch for 1996-1998 1.5L and 1997-1998 1.8L applications Fitment/availability: The inspected direct page showed In Stock and Add to Cart and explicitly lists 1996-1998 Protege 1.5L and 1997-1998 Protege 1.8L. It cro…
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Sources for this issue (3)
P0320 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 P0320 mean on a Mazda?
P0320 stands for "Ignition/Distributor Engine Speed Input Circuit Malfunction." The ECM/PCM detected a malfunction in the ignition or distributor engine-speed (RPM) input circuit. This circuit supplies the engine-speed reference used for spark timing and fuel control; a general fault here (open, short, or signal loss) is flagged as P0320. On distributorless systems this maps to the crank/ignition RPM reference. On Mazda it is documented across 2 models: 626, Protege.
What are the most common causes of P0320?
The most common causes of P0320 are: Faulty crankshaft/distributor RPM pickup sensor, Damaged wiring or connector in the RPM input circuit, Poor ground or corroded connector, Faulty ignition module, Air gap or damaged reluctor/trigger wheel. The specific cause varies by vehicle.
How much does it cost to fix P0320 on a Mazda?
Published repair estimates on Mazda range from $40 to $550 depending on the model and root cause. If an issue mentions a recall or campaign, check your VIN with the manufacturer or NHTSA and confirm eligibility and coverage with a dealer.
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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.