Parts for your 2004 Mazda Premacy-Camshaft sensor

2004 Mazda Premacy camshaft sensor — what it does, why it matters, and how to look after it

For the 2004 Mazda Premacy (first-generation CP platform, petrol and diesel), a camshaft position sensor is fitted and used by the engine management. This is confirmed in Mazda’s CP-series Workshop Manual under Engine Control System, which describes the PCM using a camshaft position (CMP) signal for cylinder identification and synchronising sequential fuel injection and ignition timing. Mazda’s Electronic Parts Catalogue for CP models also lists a camshaft position sensor across typical 1.8L/2.0L petrol and 2.0L diesel variants. Independent service data (e.g., Autodata/Autoinfo and dealer-level diagnostic references) likewise include test procedures and fault codes for the CMP on this model year.

On a 2004 Premacy, the camshaft sensor is the quiet achiever that helps the ECU know exactly which cylinder is on its compression stroke. That lets the car run proper sequential injection, time spark accurately, and keep cold starts and idle smooth as. If the CMP signal goes missing or messy, the ECU can fall back on crank-only strategies, which usually means hard starting, rough running, and a dash light that won’t quit.

Typical tell-tales of a crook camshaft sensor on this Mazda include:

• Long crank or no start when hot or cold
• Stumble, misfire, or flat spots under load
• Poor fuel economy and lazy throttle response
• Check Engine Light with codes like P0340/P0341

For servicing, there’s no routine replacement interval — it’s a monitor-and-test item. During scheduled services, a good workshop will scan for pending faults, check live CMP/CKP synchronisation, and inspect the sensor connector and loom under the bonnet for oil wicking, brittle insulation, or corrosion. Oil leaks from the rocker cover can contaminate the sensor or plug, so fixing any seep first saves headaches later.

Replacement is straightforward on most Premacy engines: disconnect the battery, unplug the connector, remove the retaining bolt, and swap the sensor with a quality OEM-equivalent. Always clean the mounting face, lightly oil the O-ring if fitted, and route the harness exactly as per factory to avoid heat soak or chafing. After installation, clear codes and verify cam/crank sync and stable idle with a scan tool. If new sensors don’t fix it, check the timing belt/chain alignment, as a jumped tooth can mimic a CMP fault.

Use genuine or reputable aftermarket parts — cheapies can introduce signal noise that plays havoc with Mazda ECUs. If the car’s doing lots of short trips or towing, consider preventative inspections a bit more often, New Zealand and Australian conditions (heat, dust, coastal humidity) can accelerate connector and insulation issues.

Popular questions about the 2004 Mazda Premacy camshaft sensor

Where is the camshaft sensor on a 2004 Premacy?

It’s typically mounted at the end of the cylinder head reading a trigger on the camshaft — often on the intake cam side. Look near the top front or rear of the engine under the plastic cover. On diesel variants, access can be tighter with extra plumbing, but it’s still at the cam end under the bonnet.

If unsure, a quick visual along the cam cover for a small two- or three-pin sensor with a single retaining bolt will usually spot it.

Can you drive with a faulty camshaft sensor?

Sometimes the car will still run by relying on the crank sensor, but starting becomes hit-and-miss and fuel economy and power can suffer. Prolonged driving risks catalyst damage from misfires and can leave the driver stranded when hot-starts fail.

Best bet is to diagnose early, fix any wiring damage, and replace the sensor if it’s out of spec.

Do camshaft sensors need calibration after replacement?

No special calibration is normally required. Fit the new sensor, clear any codes, and verify cam/crank synchronisation and idle stability with a scan tool. If issues persist, check timing alignment and the harness, as those faults won’t be solved by a new sensor alone.