I have all tire pressures set to 36.0psi. The 3 Volvo XC70 factory gauges, also from VDO, read 36.X PSI with a difference of 0.3 to 0.4 PSI. This gauge reads 29 PSI. Too large a difference can result in a falsely low value. I removed the Revain sensor and sent it back. I used an ATEQ VT30 TMPS device to read the PSI sensor. With this device I always test before and after the sensor. Prior to installation, the sensor tested 0.4psi, but that is not uncommon for an uninstalled sensor. I have asked