U0320: Software Incompatibility With Power Steering Control Module
What to do
The car steers, and it steers safely. It just does not steer the way it should.
Expect the steering to feel too light and vague, or too heavy and dead, or to wander a little on a motorway, or not to return to centre properly after a corner.
Nothing is broken. On a car with electric power steering, almost everything you would describe as "how it steers" is software — how much assistance you get for a given effort at a given speed, how the wheel returns to centre, how much of the road you feel. This code means two computers are running versions that do not belong together.
Here is why that matters: those complaints send people to the wrong parts. "It feels vague" or "it wanders" normally buys an alignment, then track rod ends, then in the worst case a steering rack — which on these cars is an extremely expensive part with the computer built into it. All of that on hardware doing exactly what it was told.
So do not agree to a steering rack, or even an alignment, on a steering feel complaint while this code is stored. Get the software sorted first, then judge the steering.
And if the steering feel changed after a dealer visit, say so — these settings do get updated, and you are not imagining it.
What this code means
A module is running software that does not belong with the power steering control module's. See U0300 for the family and U0319 for the speed-dependence argument.
Electric power steering is the clearest example in this family of software being the product rather than a setting. The hardware is a motor, a torque sensor and a gearbox. Everything a driver would describe as how the car steers is a curve stored in the module — how much assistance for a given effort at a given speed, how quickly it builds, how the wheel returns to centre, how much of the road surface is allowed through, and the small corrections applied for crosswind and road camber.
Which means a mismatch here does not usually break anything. It changes the character of the car, and the complaint arrives as a description rather than a fault: too light and vague, too heavy and dead, wandering on a motorway, not returning to centre after a turn.
That is worth naming because of what gets done about it. Those descriptions send people to the geometry, the tyres, the suspension bushes and the rack itself — an alignment that changes nothing, then a track rod end, then in the worst case a steering rack, which on an electric system is a very expensive part with the module built into it. All of that on hardware that is behaving exactly as it was told to.
So the rule is the family's, stated for the part most likely to be replaced here: do not authorise a steering rack on the strength of a steering feel complaint with a software incompatibility code stored.
Two things make this more common than it looks. Assist curves are variant-specific — the same rack carries different software for different engines, wheel sizes and markets — so a second-hand unit that fits perfectly can steer wrongly. And these modules receive calibration updates, so a vehicle whose steering feel changed after a dealer visit is describing this rather than imagining it.
Likely causes
Start here
- Second hand module locked to another vehicle · specialist
- Incorrect module configuration after replacement · specialist
- Software updated on one module only · specialist
- Software calibration out of date · specialist
Less common
- Module not coded to the vehicle · 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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What makes one worth reading:
- The car — make, model, year and engine. The same fault behaves differently on each.
- What you measured, not only what you replaced.
- What actually fixed it — or that nothing did, which is worth knowing too.
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