Question about GMC Yukon
P0172 is system running rich. Classic case of bad/dirty injectors. Have them cleaned for about $60 each, buy a cleaning kit HERE or replace them (pricey). Diagnostic Trouble Code (DTC) P0172 Fuel Trim System Too Rich Detailed Diagnostic Assistance: Note: After repairs, use the scan tool Fuel Trim Reset function to reset the long-term fuel trim to 128 (0%). Fuel pressure ? An excessively low pressure will make the system lean. Monitoring fuel pressure while driving the vehicle at various road speeds and/or loads may become necessary here. Map sensor - An output that enables the ECM to sense a manifold pressure which is less than normal (high vacuum) can drive the system lean.In such a case disconnecting the MAP sensor will permit the ECM to substitute a fixed (default) value for the MAP sensor. If disconnecting the sensor kills the lean condition then substitute a known good sensor and recheck. Fuel contamination - In trace amounts, water , near the in-tank fuel pump inlet can be added to the injector. water results in a lean exhaust condition and can set DTC P0171. Check for poor O2S or MAP sensor connection at the ECM. Inspect the harness connectors for the following conditions: Improper mating Damaged terminals Broken locks Improperly formed or Backed-out terminals Poor terminal-to-wire connection · Also examine the wiring harness to check whether there is any damage. · If the harness seems flawless, then note the O2S display on the scan tool as you move the connectors and the wiring harness related to the engine harness. · Any difference in the display will denote the location of the fault. · You must check the 5 volt reference circuits to inspect whether a short to voltage is in vogue in case you see any DTC P1404 is set. · You also need to see if there is any restricted exhaust system. · Probe the 5 volt reference sensors for abnormal readings in case a shorted 5 volt reference circuit creates a DTC P0172 to set. Thanks for using FixYa!!
Posted on Sep 25, 2009
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Posted on Jan 02, 2017
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