A fault code doesn’t yet mean the unit or sensor itself is faulty: often it’s the plug and connector leading to it.
Possible causes
- One of the devices on this bus isn’t responding: the grille shutters, an electric pump, the mass air flow sensor or others — it varies by car
- The connector of such a device by the radiator or under the bumper: water, corrosion, not latched
- The bus wire is pinched at the radiator support or chafed
- The engine ground is loose or corroded
- The wiring harness has chafed on the alternator bracket or an A/C line
- Low voltage: a flat battery or corroded terminals
What you can do yourself
- First check the battery and terminals: at low voltage the LIN bus works erratically and the unit stores extra codes.
- Look at the engine unit’s other codes: next to it there is usually a code naming the device that isn’t responding (for example, U0284 is the grille shutter, U02A9 the charge air cooler pump).
- Inspect the grille shutter and electric pump connectors by the radiator and under the bumper: water, green deposits, a connector not fully latched.
- Check the engine ground: the ground strap is tight on the engine and on the body, with no corrosion. Per a GM bulletin, a loose ground sets many communication codes at once.
- Inspect the wiring harness by and under the alternator: per a GM bulletin it chafes on the alternator bracket.
- Per GM bulletin PIP5934: if U1346 (sometimes with U060F) is only in history, clear it and check again; the mass air flow sensor isn’t replaced because of this code.
- Don’t replace the engine control unit because of this code: it only reports that a device on the bus isn’t answering.
Stop and don’t drive on if:
- The instrument panel went dark or many warning lights came on at once
- Power steering is gone or the brakes don’t work as usual
OOleg’s tip: check the connector
Often the cause is simple — there is no contact in the connector (plug). Look at the connector from the back: remove the rubber seal and you will see whether a wire is corroded or has come off completely. Corrosion shows up as green deposits. Ideally, gently pull each wire towards you one at a time: a sound wire stays in place, while a corroded one simply comes off — it needs to be repaired.
Unplug and inspect connectors with the ignition off.
LIN is a single-wire bus for “smart” devices. The meaning of U1346 is common to new GM cars (Onix, Tracker, Malibu, Tahoe), but the devices on the bus differ from car to car. This is the GM meaning (Chevrolet, Cadillac, GMC). On other makes this number means something else: if your car isn’t made by GM, change the make at the top.
Source: GM 23-NA-102, PIT5698, PIP5934, PIE0681 (static.nhtsa.gov)
On Oleg’s website:Car wiring repair ↗
The explanation comes from the error code reference in the AvtoElektrik PRO app.