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Persistent P0125 Code on 2002 Mazda ZX2: Causes and Solutions

Model: 2002 ZX2 Fault Code: P0125 Posted: 2015-07-20 19:18

My 2002 Mazda ZX2 (DOHC 2.0L) has been experiencing a recurring P0125 fault code that persists despite multiple repairs. I have already replaced the thermostat twice and the Engine Coolant Temperature Sensor (ECT) once. Each time, the check engine light was cleared, but it returns within 24 to 36 hours. Why is this happening? Am I missing a key component such as the Intake Air Temperature (IAT) sensor or Mass Airflow (MAF) sensor? The vehicle has 145,000 miles and I'm concerned about underlying issues affecting engine temperature monitoring. What steps should I take to resolve this persistent P0125 code?

Related fault codes

P0125

Comments (2)

Anonymous 2015-07-21 11:49

Is this a 2.0L Zetec or the DOHC ZX2? Ensure you're using the correct thermostat for your model year and engine configuration. Using a scanner, what temperature is the Powertrain Control Module (PCM) actually detecting—ignore the dashboard gauge as it may not reflect real engine coolant temperature.

Anonymous 2015-07-23 05:54

NOT A ZETEC — this is a DOHC 2.0L ZX2. After clearing the code, it has not returned in over 36 hours, which suggests the issue may be resolved. Before replacing the ECT, my A/C didn't work and the radiator fan ran at high speed continuously. After installing the new ECT, both issues were fully fixed — A/C functioned normally and the fan stopped running excessively. The ECT replacement solved two problems, so I’m not complaining about the outcome.