U0335: Software Incompatibility With Hybrid/EV Battery Pack Sensor Module
What to do
Do not work around this, do not have it cleared, and do not attempt anything yourself. The high-voltage system runs at several hundred volts. Expect the car to refuse to charge, refuse to deliver power, or both.
That is protection, and it is worth understanding why the car is so firm about it.
This module is the one that measures your battery — every cell's voltage, the temperatures, the current flowing. But what those measurements mean depends entirely on its software: how many cells there are, how they are grouped, which reading belongs to which physical position.
When that description does not match the pack, the car does not get obvious nonsense. It gets steady, believable numbers about a battery it is not really looking at — a cell close to its limit reported against the wrong position, or a temperature read through the wrong curve.
The entire safety case for a lithium battery rests on knowing the condition of its worst cell. With that gone, refusing to work is the only honest answer.
One thing to insist on absolutely: no second-hand module. Battery packs are revised through a car's production life — different cells, different arrangement, often under the same part number — so a used one measures your pack through the wrong description of it. A matching part number is not enough, and this is a safety matter rather than a money one.
If part of the battery has been replaced, mention it — that is the commonest cause, and the job is not finished until every computer in the pack is on the same software.
What this code means
A module is running software that does not belong with the battery pack sensor module's. See U0300 for the family and U0312 for why this corner of the corpus is stricter than the rest — and note that this concerns a high-voltage system, with nothing on it for a general workshop to open.
The distinction from U0312 is worth drawing because the two are easily confused. The battery energy control module decides what the pack may do. This module measures what it is doing — individual cell voltages, module temperatures, pack current — and reports upward.
And its software is what makes those measurements mean anything. How many cells are in series, how they are grouped, which physical position each measured channel corresponds to, what the temperature sensors' response curves are, and how raw readings map to voltages.
So a mismatch here produces measurements that are consistent, stable and describing the wrong thing — and the danger is precisely that they are believable. A cell nearing its limit reported against the wrong position, or a temperature read through the wrong curve, gives a management system confident numbers about a battery it is not actually looking at.
Which is why the vehicle stops rather than derating. The whole safety case for a lithium pack rests on knowing the condition of the worst cell, and a measurement chain that cannot be verified removes that entirely. Refusing to charge or to deliver power is the correct answer.
The U0312 warning applies here with the same force and for the same reason: no second-hand module. Packs are revised through a model's life — different cells, different grouping, different sensors, frequently under one part number — and a sensor module from a donor pack measures this one through the wrong description of it. A matching part number is not enough, and this is one of the two places in the corpus where that shortcut has physical rather than financial consequences.
A pack section replaced after a fault is the commonest route in, and the job is not complete until every module on the pack is at one calibration.
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
Less common
- Module replaced with one from another vehicle · specialist
- Interrupted module programming · specialist
- Software calibration out of date · specialist
Symptoms
Components involved
Information, not instruction
CarGeek is a reference, not a service manual. Its pages are written from public sources and from what other people have found, never from a manufacturer's own service information, so they can be wrong or incomplete for your particular vehicle. Some of what they describe carries real risk: high voltage, fuel under pressure, stored energy, hot and moving parts.
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
Be the first to write this up
Nothing posted about this yet. Whatever you found is worth writing down — even a dead end saves someone the same afternoon.
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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