P0118 2008 XC70 Intermittent coolant warning

meehaneo · Post by **meehaneo** » 04 May 2026, 07:34

I have been getting a warning "Coolant system requires servicing" irregularly over the past few weeks - whats weird is it flashes up, the orange indicator lights, then it disappears and the light goes off! But lately it has come on and stayed on, and the fans have stayed on after I park and turn the engine off. Not every time, but just today it happened.

I saw the P0118 on my cheap OBD reader, haven't plugged in VIDA yet, but looks like its either the ECT or the thermostat. Any ideas for troubleshooting? What should I check?

Ta!

Post by **volvolugnut** » 04 May 2026, 07:46

Have you examined the wires to the ECT? They may be damaged.
volvolugnut

meehaneo · Post by **meehaneo** » 04 May 2026, 14:39

I'll have a look - it looks like its under the engine cover according to VIDA. Ta!

Vova585 · Post by **Vova585** » 04 May 2026, 20:07

1. Check coolant level.
2. Inspect connector to coolant sensor for corrosion. If all good and tight fit, move to #3
3. Parts cannon aproach- replace coolant sensor($30 or so dollars). If the car has lots of miles- replace thermostat assembly. I belive it comes with sensor already(maybe $140?)
Thats would be my aproach.

meehaneo · Post by **meehaneo** » 06 May 2026, 04:07

Coolant level looks fine - will check sensor connectors - problem has not returned over the last few days, so wiring is likely suspect! I might replace sensors and thermostat at next service anyway (car is at 478,000km!)

Vova585 · Post by **Vova585** » 06 May 2026, 08:36

Is that diesel or 3.2? Respectful miles especially for Ireland
I never worked on 3.2, but heard that they are bulletproof(minus read unit, alternator coupler bolt). Given "old" design of the engine, it likely does not need to have vaccum coolant replacement like in new 4cyl engines.

meehaneo · Post by **meehaneo** » 10 May 2026, 05:02

Vova585 wrote: 06 May 2026, 08:36 Is that diesel or 3.2? Respectful miles especially for Ireland
I never worked on 3.2, but heard that they are bulletproof(minus read unit, alternator coupler bolt). Given "old" design of the engine, it likely does not need to have vaccum coolant replacement like in new 4cyl engines.

It's the 5 cylinder diesel 2.4

meehaneo · Post by **meehaneo** » 15 May 2026, 04:44

Just following up for anyone with a similar problem - I popped off the top engine cover and could easily see the thermostat housing. It looked quite "shiny" so I guess it had been replaced at some point. I disconnected the temperature sensor, and sprayed some contact cleaner on the plug and socket. I let it dry, and then reconnected. At this point its been about a week and the problem has not returned, so fingers crossed it was just a dirty or loose connection! Thanks for pointers, everyone.