Cause
Excessive load or towing
The engine genuinely working harder than its cooling and aftertreatment were sized for — towing, a full load, a long climb, or high ambient temperature. It is a condition rather than a fault, and the codes it produces are the protection systems doing their job.
Coolant and oil temperature rise, exhaust temperature rises, and the module derates to protect the engine. All of that is designed behaviour. A code that appears only while towing and never otherwise is describing the load, not a component, and the vehicle will test perfectly the following day.
The useful question is whether the load is within specification. Towing capacity, nose weight and gross train weight are stated by the manufacturer for exactly this reason, and a combination beyond them will overheat a vehicle in perfect condition. Ask what the vehicle was doing when the fault appeared. Where the load is legitimate and the vehicle still overheats, the cooling system has lost margin — a partly blocked radiator or a tired fan shows up under tow and nowhere else.
Typically an easy fix. Often worth checking before paying anyone to look.
Some of these codes mean you should stop driving
2 of the 2 codes this can cause indicate a fault where continuing to drive risks damage or is unsafe. Which one you have matters more than the cause does — read the code's own page before deciding.
Codes this can cause (2)
Codes where this is a likely explanation first, rather than merely a possible one.
Information, not instruction
CarGeek is a reference, not a service manual. Its pages are written from public sources and from what other people have found, never from a manufacturer's own service information, so they can be wrong or incomplete for your particular vehicle. Some of what they describe carries real risk: high voltage, fuel under pressure, stored energy, hot and moving parts.
Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
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Nothing posted about this yet. Whatever you found is worth writing down — even a dead end saves someone the same afternoon.
What makes one worth reading:
- The car — make, model, year and engine. The same fault behaves differently on each.
- What you measured, not only what you replaced.
- What actually fixed it — or that nothing did, which is worth knowing too.
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