What does it mean?
C1727 is a Chassis (ABS, traction control, steering) fault code. It indicates: Battery Voltage of LR Transmitter Drops. .
Symptoms
- Tyre pressure warning lamp flashing on start-up and then illuminating steadily
- Left rear pressure value blank, frozen or appearing only for a short time after driving
- System fault message rather than a low pressure message
- All tyres measure correctly with a hand gauge yet the fault stays
- Fault reappears after each relearn attempt
Likely causes
- Sealed cell in the left rear sensor exhausted after normal service life
- Internal fault preventing the sensor from entering sleep mode, draining the battery quickly
- Repeated deep cold reducing the cell's ability to deliver current
- Water or sealant contamination inside the wheel damaging the sensor board
- Physical damage to the sensor from a kerb strike or a careless tyre change
- Non-original or previously used sensor with little battery life left
- Poor signal path to the receiver from that corner, logged as a low battery
How to fix it
- Check TPMS live data for which corner is silent and what battery status is reported
- Use a TPMS tool to trigger the left rear sensor directly and observe the response
- Verify that the stored ID for the left rear location is the sensor actually fitted there
- With the tyre dismounted, inspect for sealant, corrosion and a cracked sensor housing
- Replace the left rear sensor, since the internal battery is not serviceable
- Program the ID, complete the relearn and confirm every position transmits pressure
- Note the age of the remaining sensors and recommend replacing the set if they are of the same vintage