EngineNewsCommunity Starter

G37 runs hot at idle but cools once moving

TurboBuilder93Community StarterJul 27, 20262013 Infiniti G37 xSCalifornia
Temperature creeps up sitting still and drops once road speed gives it airflow. Fans appear to run, but I haven't checked actual commanded speed. Any good way to diagnose airflow versus coolant circulation without guessing?
permalink

25 replies

TireTraveler65Community StarterCommunity StarterJul 27, 2026permalink
Intermittent stuff lies if you only catch it once. Loaded-suspension checks on the 2013 Infiniti G37 catch play that a wheels-hanging inspection misses. Don't erase codes until someone who can help has seen them. On “g37 runs hot at idle but cools,” that was the fork that mattered for me. The universe charges extra for guessing. If it repeats twice more I'll book time.
CruiseBuilderCommunity StarterCommunity StarterJul 27, 2026permalink
This is usually cheaper to test than to guess. Two 2013 Infiniti G37s can feel identical and have different causes, so measure before you copy someone else's repair. If the cheap test changes it, stop and reassess. This is from a 2013 Infiniti G37 in California. Did the worksheet show tax yet? That's my plan before I call anyone.
JDMHunterCommunity StarterCommunity StarterJul 27, 2026permalink
If it were in my driveway, capture voltage while the 2013 Infiniti G37 is actually failing — after it restarts you've lost the clue. That's the branch I'd chase this week. Time, temperature, and whether it's in gear are the notes that actually help a shop. Not trying to scare you — just skip the expensive first guess. Trying not to diagnose from the couch.
CruiseTuner71Community StarterCommunity StarterJul 27, 2026permalink
I wouldn't throw parts yet. Swap the cheap/easy piece first on the 2013 Infiniti G37 and see if the fault moves. That's the branch I'd chase this week. Keep sale price, fees, and rate as three different conversations. I've seen both outcomes, which is why I'd test instead of assume. Doing the boring step first on purpose.
CruiseTuner71Community StarterCommunity StarterJul 27, 2026permalink
Log the conditions before you spend. A pressure test beats staring at a dry driveway if the 2013 Infiniti G37 is losing coolant with no puddle. You'll know quickly if you're on the wrong tree. On “g37 runs hot at idle but cools,” that was the fork that mattered for me. Keep sale price, fees, and rate as three different conversations. If this is nothing, great. I want that in data.
CruiseBuilderCommunity StarterCommunity StarterJul 28, 2026permalink
Yes, with one caveat: Two 2013 Infiniti G37s can feel identical and have different causes, so measure before you copy someone else's repair. If the cheap test changes it, stop and reassess. When does it actually happen? I'm in no rush to be a hero on it.
JDMHunterCommunity StarterCommunity StarterJul 27, 2026permalink
Log the conditions before you spend. If a shop can't duplicate it on the 2013 Infiniti G37, bring a video plus freeze-frame data, not just a story. That's the branch I'd chase this week. On “g37 runs hot at idle but cools,” that was the fork that mattered for me. This is from a 2013 Infiniti G37 in California. Time, temperature, and whether it's in gear are the notes that actually help a shop. If your situation is the opposite, ignore me. If this is nothing, great. I want that in data.
JDMHunterCommunity StarterCommunity StarterJul 27, 2026permalink
That's a good start, but I wouldn't stop there. Two 2013 Infiniti G37s can feel identical and have different causes, so measure before you copy someone else's repair. Don't erase codes until someone who can help has seen them. Write the result down so the next test isn't a repeat of the last one. Make the next action something you can finish this week. I'm in no rush to be a hero on it.
CruiseTuner71Community StarterCommunity StarterJul 27, 2026permalink
Start with the test that can prove you wrong. Capture voltage while the 2013 Infiniti G37 is actually failing — after it restarts you've lost the clue. That's the branch I'd chase this week. Keep sale price, fees, and rate as three different conversations. Only after sitting overnight so far.
JDMHunterCommunity StarterCommunity StarterJul 27, 2026permalink
This is usually cheaper to test than to guess. Write temp, speed, and in-gear vs coast when the 2013 Infiniti G37 does it — then decide on parts. Save the big job until that test fails. This is from a 2013 Infiniti G37 in California. Keep sale price, fees, and rate as three different conversations. Not driving it hard until I know more.
CruiseBuilderCommunity StarterCommunity StarterJul 28, 2026permalink
I hear you, though I'd still want a second check. A pressure test beats staring at a dry driveway if the 2013 Infiniti G37 is losing coolant with no puddle. If the cheap test changes it, stop and reassess. Have you gotten a second quote in writing? Not trying to scare you — just skip the expensive first guess. That's my plan before I call anyone.
CruiseBuilderCommunity StarterCommunity StarterJul 27, 2026permalink
Log the conditions before you spend. Move a coil or plug on the 2013 Infiniti G37 if it's cylinder-specific and see whether the code follows. Save the big job until that test fails. On “g37 runs hot at idle but cools,” that was the fork that mattered for me. When does it actually happen? Video is ugly but it shows the hesitation.
TurboBuilder93Community StarterCommunity StarterJul 28, 2026permalink
Checked the easy stuff on the 2013 Infiniti G37 and found one clue worth chasing before I book a shop. Wrote this up on my lunch break.
JDMHunterCommunity StarterCommunity StarterJul 28, 2026permalink
Ask what changed right before it started. Capture voltage while the 2013 Infiniti G37 is actually failing — after it restarts you've lost the clue. Save the big job until that test fails. This is from a 2013 Infiniti G37 in California. Keep sale price, fees, and rate as three different conversations. Parking it somewhere I can hear it better next time.
TurboBuilder93Community StarterCommunity StarterJul 28, 2026permalink
OP here — recorded a short video and noted speed, temp, and whether it was in gear. If this is nothing, great. I want that in data.
TireTraveler65Community StarterCommunity StarterJul 28, 2026permalink
Start with the test that can prove you wrong. Get a real battery/charging test on the 2013 Infiniti G37, not just resting voltage, before blaming a module. You'll know quickly if you're on the wrong tree. Monthly payment math is how wallets disappear. Might be overthinking it, but I'd rather overthink than overspend.
CruiseTuner71Community StarterCommunity StarterJul 29, 2026permalink
Fair point. Counterpoint: Capture voltage while the 2013 Infiniti G37 is actually failing — after it restarts you've lost the clue. Don't erase codes until someone who can help has seen them. Keep sale price, fees, and rate as three different conversations. Not interested in a five-hour wait for a shrug.
TireTraveler65Community StarterCommunity StarterJul 28, 2026permalink
I wouldn't throw parts yet. Two 2013 Infiniti G37s can feel identical and have different causes, so measure before you copy someone else's repair. Save the big job until that test fails. The universe charges extra for guessing. Worth doing even if the car feels fine right now. Parking it somewhere I can hear it better next time.
CruiseBuilderCommunity StarterCommunity StarterJul 28, 2026permalink
Log the conditions before you spend. Swap the cheap/easy piece first on the 2013 Infiniti G37 and see if the fault moves. Save the big job until that test fails. On “g37 runs hot at idle but cools,” that was the fork that mattered for me. Did the worksheet show tax yet? Heat soak after errands is the other window.
TurboBuilder93Community StarterCommunity StarterJul 28, 2026permalink
Update: the cheap test changed the symptom, so I'm not throwing parts yet. Wrote this up on my lunch break.
CruiseBuilderCommunity StarterCommunity StarterJul 28, 2026permalink
Asking because it changes the advice: If a shop can't duplicate it on the 2013 Infiniti G37, bring a video plus freeze-frame data, not just a story. Don't erase codes until someone who can help has seen them. This is from a 2013 Infiniti G37 in California. When does it actually happen? Make the next action something you can finish this week. Cold start is when I can actually reproduce it.
CruiseTuner71Community StarterCommunity StarterJul 28, 2026permalink
I'd want a measurement, not a hunch. Two 2013 Infiniti G37s can feel identical and have different causes, so measure before you copy someone else's repair. Don't erase codes until someone who can help has seen them. Write the result down so the next test isn't a repeat of the last one. Not interested in a five-hour wait for a shrug.
CruiseTuner71Community StarterCommunity StarterJul 29, 2026permalink
Yes, with one caveat: Write temp, speed, and in-gear vs coast when the 2013 Infiniti G37 does it — then decide on parts. That's the branch I'd chase this week. Write the result down so the next test isn't a repeat of the last one. I'd sleep better after that step, even if it finds nothing. Might be overthinking it, but I'd rather overthink than overspend.
CruiseTuner71Community StarterCommunity StarterJul 29, 2026permalink
That's a good start, but I wouldn't stop there. A pressure test beats staring at a dry driveway if the 2013 Infiniti G37 is losing coolant with no puddle. Don't erase codes until someone who can help has seen them. This is from a 2013 Infiniti G37 in California. Keep sale price, fees, and rate as three different conversations. If the story changes I'll post the new data.
JDMHunterCommunity StarterCommunity StarterJul 29, 2026permalink
Agree — and I'd add this: Loaded-suspension checks on the 2013 Infiniti G37 catch play that a wheels-hanging inspection misses. Save the big job until that test fails. On “g37 runs hot at idle but cools,” that was the fork that mattered for me. Time, temperature, and whether it's in gear are the notes that actually help a shop. If your situation is the opposite, ignore me. Doing the boring step first on purpose.
Sign in to reply

Similar discussions