U3570 code meaning
Stack Inlet Coolant Temperature Sensor Circuit
Network system Generic code U35xx codes Check engine light
What U3570 means
U3570 signals that the sensor for coolant entering the stack sends a broken, shorted or out-of-range reading. Thermal control is steered by this value: Hyundai describes a three-port valve which gets the stack inlet temperature from the fuel cell control unit over CAN and sets its opening from it, and in a Nissan patent the current drawn from the stack is capped once inlet coolant passes a set point, so that the outlet cannot overheat. GM shows that the inlet figure can also be estimated from pump inlet temperature, flow rate and a heat exchanger model. No maker documents U3570 publicly. Without a valid reading the system has to run on a substitute; a warning lamp and held-back power are to be expected. Outlet sensors report as U3571 and U3572.
U3570 at a glance
- Check engine lightYes, usually on
- Emissions testNot an emissions code
- Limp modePossible
- Repair difficultyHard
- Typical labor0.5 to 2.5 hours
- Clears after repairWhen cleared with a scanner
Symptoms of U3570
- Fuel cell system warning, MIL on
- Reduced power, especially under high load
- Implausible stack inlet temperature in live data
Common causes of U3570
- Most likelyOpen, short or corrosion in wiring or connector of the inlet sensor
- PossibleInlet coolant temperature sensor faulty internally (drift, internal open)
- Less likelyCoolant seeping past the sensor seal into the connector
- Less likelyInput stage of the fuel cell control unit faulty
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Stack inlet coolant temp sensorSensor wiring
What each part of U3570 means
| U | Network system: communication between the control modules (CAN bus). |
| 3 | Reserved range, usually generic. |
| 70 | The exact fault in that area. |
What to do next
- Note U3570 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about U3570
What does U3570 mean?
U3570 means "Stack Inlet Coolant Temperature Sensor Circuit". U3570 signals that the sensor for coolant entering the stack sends a broken, shorted or out-of-range reading. It is a generic code, so it means the same on every make.
Is it safe to drive with U3570?
Drive gently and only to a workshop. With U3570 the car can go into limp mode (reduced power) to protect itself.
Will U3570 fail an emissions test?
U3570 is not an emissions code, so on its own it usually does not fail an emissions test. Other stored codes or a lit check engine light still can.
How hard is U3570 to fix?
Difficulty: hard. A typical repair takes 0.5 to 2.5 hours of work. This is a job for a workshop.
Will U3570 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.