U0317: Software Incompatibility With Park Brake Control Module
What to do
Two things to establish first, and they need different reactions.
If the parking brake will not apply, you have no parking brake. Use the gearbox's park position, turn your wheels into the kerb on any slope, and avoid leaving the car on a gradient. There is no lever or cable to fall back on.
If it will not release, stop. Driving with the rear brakes partly on generates a lot of heat very quickly. A smell of hot brakes, a feeling of dragging, or hot rear wheels after a journey means pull over.
And here is the one that costs money, which is the real reason for this page.
If your rear brake pads are due, do not let them be changed until this is fixed. Electric parking brake pistons are driven by little motors and have to be wound back electronically — a "service mode" the garage commands with a tool. A software mismatch can leave that mode unavailable.
And what sometimes happens then is that somebody forces the piston back with a clamp, the way you would on an ordinary brake. On these it drives the motor and gearbox backwards and destroys the caliper — turning a routine pad change into two new calipers.
So: software first, brakes second. Say this to the garage in those words if pads are on the job sheet.
What this code means
A module is running software that does not belong with the park brake control module's. See U0300 for the family and U0301 for why the named module is not the accused.
An electric park brake is two motors on the rear calipers and no cable, and the consequences of that split in two directions worth stating separately.
If it will not apply, the vehicle has no parking brake. Use the transmission's park position, turn the wheels into the kerb on a slope, and do not leave it on a gradient — there is no lever to fall back on and no cable tension to feel.
If it will not release, the vehicle is being driven with the rear brakes partly clamped. That generates heat quickly — overheated pads and discs, and on a long journey a genuine fire risk. A smell of hot brakes, a sense of dragging, or hot rear wheels after a journey means stopping.
But the reason this page exists is a third thing, and it costs people money in a way the first two do not: service mode.
An electric park brake's caliper pistons are driven by motors through a screw, and they must be wound fully back electronically before rear pads can be changed. That is what service mode does, and it is commanded over the network. A software mismatch can leave service mode unavailable — the tool asks, and the module will not comply.
What happens next is the expensive part. A workshop that meets a caliper it cannot retract sometimes forces the piston back with a clamp, as it would on a conventional caliper. On an electric one that drives the screw mechanism backwards through its motor and gearbox and destroys it — turning a pad change into two calipers.
So the instruction is unambiguous: if service mode is unavailable, the pads do not get changed until it is. This is a software fix first and a brake job second, in that order, and reversing them is what turns a modest bill into a large one.
Likely causes
Start here
- Software updated on one module only · specialist
- Incorrect module configuration after replacement · specialist
- Second hand module locked to another vehicle · specialist
Less common
- Module not coded to the vehicle · specialist
- Software calibration out of date · specialist
- Interrupted module programming · specialist
Symptoms
Components involved
Information, not instruction
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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.
Community experience
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