Powertrain, generic · Fuel and air metering

P0168 Fuel Temperature Too High

Check engine lightOn
EmissionsNot relevant
Drive cycleNot required
Limp modePossible

P0168 is not a sensor fault but an operating condition, almost only on diesels: the fuel temperature sensor reports fuel hotter than a protective limit. The fuel heats up through the return flow from the high-pressure pump and injectors, especially with little fuel in the tank, at idle after full load, in hot weather or with a failed fuel cooler; one manufacturer patent names about 80 °C as the upper limit to protect seals, against a normal range of roughly 5–60 °C. On Saab's Bosch EDC16 diesels the code means an engine protection function is active and injection quantity is reduced. No manufacturer threshold was found, and GM's and Ford's diesel summaries do not use P0168. Whether the warning light comes on depends on the manufacturer.

Likely causes

Fuel cooler (air or water cooler in the return) dirty or faulty, coolant circuit disturbed
Very little fuel in the tank at high load or heat
Excessive return flow from worn high-pressure pump or injectors, or faulty overflow valve
Fuel temperature sensor drifting and reading too high
Engine overheating or overload (trailer, gradient)

Symptoms

  • Loss of power, limp mode (reduced injection quantity)
  • Warning light depending on manufacturer
  • Occurs in heat, at full load, with little fuel in the tank

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€80–600
Time1–3 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

fuel temperature sensor afuel coolerfuel return line

Related codes

P0181P0182P0183P0217P0087P008F

References: law.cornell.edu, saabwisonline.com, patents.google.com.