#coolant
6 posts in Car Diagnostics blog about "coolant" — OBD-II diagnostics, DTC codes, repair. ← All posts
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Steam from under the bonnet: stop or drive on?
The decision has to be made in about ten seconds, and getting it wrong turns a cheap hose into a cylinder head. Here is how to read the situation from the driver seat.
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Temperature gauge going up and down: thermostat or air lock
A needle that will not settle is telling you coolant flow is intermittent. Whether that is a lazy thermostat, trapped air or a failing pump is decided by when it happens.
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Coolant: why colours must not be mixed and what to do if they were
Coolant colour guarantees nothing — the additive package is what matters. The types, the consequences of mixing, and how it shows up in diagnostics.
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Engine overheating: what to do in the first two minutes, and why the gauge lies
Overheating is one of the few cases where stopping correctly matters more than diagnosing correctly. The action sequence, six causes, and why the dashboard needle should not be trusted.
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Coolant Leak Diagnosis: OBD-II Detection Before Overheating
How to detect coolant leaks through OBD-II: P0128 thermostat, P0116 ECT sensor, P0217 overheat — step-by-step diagnosis and causes. Catch it before engine damage.
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P0128: why the engine won't warm up — thermostat, sensor or something sneakier
Deep dive into P0128: when it appears, why thermostats fail stuck open, how to diagnose without teardown, and why a "cold" engine burns 10-15% more fuel.