How TPMS Works

System Indicator Locations
The system has two indicators.
^ The low tire pressure indicator (A)
^ The TPMS indicator (B)





How TPMS Works
The TPMS (tire pressure monitoring system) has a low tire pressure indicator and a TPMS indicator. When the TPMS control unit detects low pressure in a tire, or a problem in the system, it turns on the appropriate indicator.

^ If low tire pressure is detected in one or more tires, the low tire pressure indicator comes on.
^ If a problem in the system is detected, the TPMS indicator comes on.
^ If low tire pressure and a problem in the system are detected, only the TPMS indicator comes on.

If the system is OK, the TPMS indicator and the low tire pressure indicator should come on when you turn the ignition switch to ON (II), and then go off 2 seconds later. If they don't, there is a problem with the system.

If the system detects low pressure in any of the four tires, the low tire pressure indicator comes on, and the control unit sets one or more of these codes:

DTC 11, 13, 15, 17. When the tire pressure returns to normal, the control unit turns off the indicators and stores the DTC(s). However, if the control unit detects a problem in the system during an indication of low tire pressure, it turns off the low tire pressure indicator, stores the DTC(s), and turns on the TPMS indicator(s).

NOTE: Tire pressure increases slightly as the temperature in the tires rises during driving at highway speeds. Pressure also increases or decreases slightly with changes in outside air temperature. A temperature change of about 18°F (10°C) changes tire pressure by about 10 kPa (0.1 kgf/cm2, 1.5 psi). If the temperature drops, tire pressure could decrease just enough to turn on the low tire pressure indicator, but later, the tire temperature could increase enough to turn the indicator off. To resolve a complaint of such intermittent indications, confirm and clear the stored DTC(s) and check the tire pressures. Then explain to the customer how temperature changes can affect the system, especially when tire pressures are near the low end of the TPMS normal range - 168 to 220 kPa (1.7 to 2.2 kgf/cm2, 24 to 32 psi).

If a problem is detected in the system, the TPMS indicator comes on and stays on until the system returns to normal with most DTCs. If DTC 81, 83, or 85 is set, the TPMS indicator goes off only when the ignition switch is turned to LOCK (0).

When a flat tire is replaced with the spare tire, the TPMS indicator comes on (DTC 32, 34, 36, or 38) because the system is no longer receiving the signal from the flat tire's transmitter.
This is not a problem with the spare tire.

Problems That Are Not System Faults
^ Tire Sealant
Fluid sealant used to repair a punctured tire can damage the tire pressure sensor mounted in each wheel. It can prevent the system from detecting the correct tire pressure, which sets a DTC 11, 13, 15, or 17 even though the system is normal.
^ Cold Weather
When the weather is extremely cold - about -40°F (-40°C) or colder - the output of the lithium battery in each tire pressure sensor may drop far enough that the control unit sets a DTC for low battery voltage (31, 33, 35, or 37) even though the system is normal.
^ Non-TPMS Wheels
Vehicles equipped with TPMS must use wheels made for the system. Every TPMS wheel has an exclusive mark; do not use any other type of wheel.

How a Diagnostic Trouble Code (DTC) is Set
^ When the system detects a problem, the TPMS control unit sets a code, but shifts to fail-safe mode, and will not alert the driver to low tire pressures.
^ If the TPMS control unit loses power, or fails, the TPMS indicator comes on, but no DTC is set.
^ The memory can hold all the DTCs that could possibly be set. However, when the same DTC is detected more than once, the most recent one overwrites the previous one, so only the latest DTC of each type is stored.
^ DTCs are indicated in ascending order, not in the order they occurred.
^ Set DTCs are stored in the EEPROM (nonvolatile memory), they cannot be cleared by disconnecting the battery. To clear a DTC, connect the HDS (Honda Diagnostic System) to the data link connector (DLC), and follow the screen prompts.