DTC P0108: EGR Boost Sensor: Condition

This DTC indicates EGR Barometric pressure sensor EGR boost sensor input signal is out of self-test range. Possible causes for this fault are:

Check EGR Boost Sensor VREF Voltage

Turn ignition off. Disconnect EGR boost sensor. Turn ignition on. Measure voltage between SIG RTN terminal and VREF terminal at EGR boost sensor wiring harness connector. If voltage is 4-6 volts, go to next step. If voltage is not 4-6 volts, repair open VREF circuit.

Check EGR Boost Circuit Resistance

Leave EGR boost sensor disconnected. Turn ignition off. Disconnect PCM 104-pin connector. Inspect for damaged pins and repair if necessary. Connect Breakout Box (014-00950), leaving PCM disconnected. Measure resistance between test pin No. 91 (SIG RTN) and SIR RTN terminal at EGR boost sensor wiring harness connector. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in SIG RTN circuit and repeat QUICK TEST. See TESTS W/CODES - INTRODUCTION article.

Check EGR Boost Circuit For Short To Ground Or Power

Leave ignition off and EGR boost sensor disconnected. Measure resistance between test pin No. 34 and test pins No. 71 (VPWR), 90 (VREF), and 97 (VPWR) at breakout box. If each resistance measurement is 10 k/ohms or more, go to next step. If any measurement is less than 10 k/ohms, repair short in EGR boost circuit and repeat QUICK TEST. See TESTS W/CODES - INTRODUCTION article.

Check EGR Boost Sensor Response

Leave ignition off. Disconnect vacuum hose between EGR boost sensor and EGR boost solenoid. Inspect hose for damage and repair if necessary. Connect vacuum pump to EGR boost sensor vacuum port. Turn ignition on. While measuring voltage between test pins No. 34 (EGR boost) and 51 (PWR GND), slowly apply 21 in. Hg. If voltage response is 0.8-1.5 volts, go to step 5). If voltage is not as specified, replace EGR boost sensor and repeat QUICK TEST. See TESTS W/CODES - INTRODUCTION article.