PACCAR MX P0168 is the fault code page for “Fuel temperature – Data valid but too high, most severe” in the 2013 PACCAR MX Diagnostic Service Manual. PACCAR publishes it for engines in the EPA 2013 emissions family, and it is worked with the DAVIE diagnostic software.
What this fault code means
Fuel temperature is measured by sensor F803 in the low-pressure fuel supply gallery between the common rail pump units. It blocks automatic fuel module water draining when the water may be frozen, and limits engine torque when the fuel gets too hot.
Set and reset conditions
The diagnostic runs continuously with the ignition on and sets when the PCI ECU D420 sees fuel temperature above 98 C for more than 30 seconds. To validate a repair, key off 15 seconds, key on, then start and idle over 30 seconds.
PACCAR MX P0168 wiring and technical data
The sensor uses a signal and a ground circuit into connector D420.A, with a published resistance curve. The fault code information block records it as 1 trip red fault lamp, 3 drive cycle recovery, readiness group none, freeze frame type Fuel.
| D420 pin | F803 pin | Function |
|---|---|---|
| A42 | 1 | Signal, fuel temperature |
| A60 | 3 | Ground |
| – | 1 to 3 | 2411 to 2573 ohm at 20 C |
Possible causes and working notes
- Restriction in the fuel return to tank circuit
- Faulty fuel pressure regulating valve
- Excessive fuel dumping through pressure release valve L094
This is a red fault lamp code and engine torque is reduced while it is active, so the driver will notice. The manual points at fuel pressure checks first: hot fuel is usually a return-circuit or regulating-valve story.
Document details and format
| Field | Value |
|---|---|
| Brand | PACCAR |
| System group | DTCs, MX Engines (EPA2013) |
| Source publication | 2013 PACCAR MX Diagnostic Service Manual |
| Manual page | 161 |
| Pages | 5 |
| File size | 0.6 MB |
| Format | PDF, English |
Applies to PACCAR MX P0168 repairs
The page sits in the DTCs section for MX engines built to the EPA 2013 emissions standard, so it covers trucks running that engine family with the PCI engine control unit. Coverage and dealer support are published on the PACCAR corporate site.
Who needs this PACCAR MX P0168 page
Fleet shops with a hot-fuel derate on a PACCAR MX engine, where the code is a plausibility result, not a circuit failure.
The full PDF page is in the DiagTechPro manuals library; a free account downloads it. Keep the PACCAR MX P0168 sheet open next to DAVIE.
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