Symptoms of U0315
- Check-engine light, sometimes with several unrelated codes at once.
- Warning lights, a no-start, or intermittent electrical faults.
- Communication or module-reset problems on a scan tool.
Common causes of U0315
- Low battery voltage, poor grounds, corroded connectors, or blown fuses.
- Wiring or network (CAN bus) faults between modules.
- A module software/programming issue, or rarely a failed controller.
Useful checks before replacing parts
- Establish what changed immediately before the code appeared — a replaced module, an interrupted reflash or a partial software update is the usual trigger for an incompatibility fault.
- Compare the calibration and part numbers actually programmed into each module against what the manufacturer specifies for this vehicle by VIN.
- Check for outstanding software campaigns or service bulletins, because the fix for an incompatibility fault is frequently a specified update rather than any hardware work.
How serious is U0315, and can you keep driving?
- Urgency
- Varies — read the whole code list before judging
- Safe to drive?
- Depends entirely on what the module has decided to do about it.
This family covers control-module, reference-voltage and internal-fault codes, and the severity spans the full range. A failed reference voltage can put several unrelated sensors out at once, which is why a car with one of these often has a long code list rather than a single entry. Read the whole list: the pattern across the codes usually identifies the common circuit far faster than any one of them does.
Clearing U0315, and making it stay gone
Clearing U0315 with a scan tool switches the lamp off; it does not fix anything, and it throws away the freeze-frame snapshot the car saved when the fault set. That snapshot is the most useful diagnostic evidence you have, because it records the load, RPM and temperature at the moment the test failed. Read it before you erase it.
Left alone, the lamp goes out on its own once the monitor that failed runs and passes on three consecutive driving cycles. The code stays in history after that, which is how a workshop can still see it. Disconnecting the battery is not a shortcut — it clears the stored codes and every learned fuel-trim value with them, so the car relearns from scratch and the underlying fault simply sets the code again.
On vehicles from roughly 2010 onward there is also a permanent DTC, which no scan tool can erase at all. It clears only when the monitor genuinely passes. That is deliberate: it stops a code being wiped in the car park outside an emissions test.
What U0315 costs to put right
There is no honest single figure for U0315, and any page that gives you one is guessing. The code names a circuit or a failed monitor, not a part — the same code can be a chafed wire, a connector full of water, or the component itself, and those are three very different bills.
The number worth budgeting for is diagnostic time. An hour of it is almost always cheaper than the second part you buy after the first one does not fix it, and parts fitted on a guess are rarely refundable once installed. If you are getting a quote, ask what the diagnosis found rather than what is being replaced — a computer fault traced to a specific cause is a repair, and a list of parts is a hopeful shopping list.
Questions people ask about U0315
What does U0315 mean?
U0315 means the modules on the network disagree about which software or calibration they should be running, with the ABS control module identified as the mismatch. This normally follows a module replacement, a reflash, or a partly completed update.
Can I drive with U0315?
Depends entirely on what the module has decided to do about it. This family covers control-module, reference-voltage and internal-fault codes, and the severity spans the full range. A failed reference voltage can put several unrelated sensors out at once, which is why a car with one of these often has a long code list rather than a single entry. Read the whole list: the pattern across the codes usually identifies the common circuit far faster than any one of them does.
What causes U0315?
The usual candidates are low battery voltage, poor grounds, corroded connectors, or blown fuses; wiring or network (CAN bus) faults between modules; a module software/programming issue, or rarely a failed controller. The code tells you which test failed, not which of those did it — that is what the checks on this page are for.
Will U0315 clear itself?
Left alone, the lamp goes out on its own once the monitor that failed runs and passes on three consecutive driving cycles. The code stays in history after that, which is how a workshop can still see it. Disconnecting the battery is not a shortcut — it clears the stored codes and every learned fuel-trim value with them, so the car relearns from scratch and the underlying fault simply sets the code again.
Does U0315 mean I need to replace a part?
Do not treat this as a wiring fault or replace hardware. The modules are communicating perfectly well; they are disagreeing about software, and only correct programming resolves it.
How much does it cost to fix U0315?
There is no honest single figure for U0315, and any page that gives you one is guessing. The code names a circuit or a failed monitor, not a part — the same code can be a chafed wire, a connector full of water, or the component itself, and those are three very different bills.
Related OBD-II codes
These nearby computer entries can help compare wording and pin down the fault area.