U1403: On Chrysler vehicles, U1403 means the fuel level signal received over the network is implausible
Fuel level, serial communication, implausible signal
Severity: Severity not verified — if the car runs badly, have it inspected
The sources describe a fuel gauge and warning light problem, but none states how safe the vehicle is to drive, so we have not assigned a class.
U1403 in short
On Chrysler vehicles, U1403 means the fuel level signal that a module received is implausible. Owners report a gauge that drops to empty with fuel in the tank and a check engine light. We have no source rating the risk, so have it checked, and keep track of the fuel yourself meanwhile.
The fuel level sender in the tank reports how full it is. That reading travels to the instrument cluster and over the data bus to other modules. When the value that arrives makes no sense, a module stores U1403. A reference page words it as a fuel level, serial communication, implausible signal fault for Chrysler.
The same reference lists wiring, the instrument panel, the CAN data bus, the front multifunction control module and the engine control module as probable causes, so the code alone does not say which part is at fault.
A 2007 Pacifica owner reports the gauge dropping to zero with fuel in the tank and the light staying on after dealers replaced fuel pumps. A 2008 Sebring owner read the code after the instrument panel lights flashed and the car would not take a jump. These are single owner accounts, not confirmed repairs.
Pick your make
U1403 is a manufacturer-specific code: its meaning depends on who built the car.
Other makes: meaning not verified. Check with a scan tool that reads manufacturer definitions.
Most likely causes
These are general causes for this code across vehicles. None is specific to one make or model.
Cause 1: Fuel level sender or fuel pump module signal fault
Possible — needs testing- Why it ranks here
- A Pacifica owner links the gauge dropping to zero with U1403, and dealers reportedly replace fuel pumps; the owner says that often fails to fix it, so the evidence is weak.
- What would change this
- Rises if the scan tool fuel level reading is erratic or stuck while the tank is full. Falls if the reading is steady and correct but the gauge or code still fails.
Cause 2: Instrument cluster or data bus fault
Possible — needs testing- Why it ranks here
- The reference page lists the instrument panel and CAN data bus among probable causes, and the Sebring owner saw cluster lights flashing when the code appeared.
- What would change this
- Rises if other gauges or warning lights misbehave together or other network codes are stored. Falls if only the fuel gauge is wrong.
Cause 3: Wiring or power supply fault
Possible — needs testing- Why it ranks here
- The reference page lists wiring, and the Sebring owner had a dead-car electrical failure at the time, though the owner only suspects a link.
- What would change this
- Rises with intermittent faults that change with bumps or battery voltage. Falls if all circuits test normal.
What to test first
Start at step 1. Each result tells you what it means and where to go next.
Step 1: Read all codes and compare the scan tool fuel level reading with the gauge and with how much fuel is in the tank.
IfThe scan tool fuel level reading is wrong or erratic
It meansThe sender or its signal is the likely source.
IfThe scan tool reading is correct but the gauge is wrong, or other cluster faults appear
It meansSuspect the cluster or the data bus.
Step 2: Have a technician test the fuel level sender signal and its wiring at the tank connector.
Warning:Working near the fuel tank and pump exposes fuel vapor and ignition risk; leave this to a shop.
IfThe signal is erratic or out of range
It meansRepair the sender or pump module and recheck.
Points to: Fuel level sender or fuel pump module signal fault
IfThe signal is normal
It meansMove on to the cluster and bus.
Step 3: Have a technician check the data bus circuits, the cluster and module power and grounds, and look for other stored network codes.
Warning:Probing live module circuits can damage electronics; do not disconnect modules or backprobe airbag circuits without the service procedure.
IfBus or cluster faults are found
It meansRepair and retest.
IfPower or ground faults are found
It meansRepair the wiring and retest.
Symptoms
- Fuel gauge reads empty or stuck with fuel in the tank
- Low fuel warning on with a full tank
- Check engine light
- Instrument cluster lights flashing
How to fix
Parts and cost context
- Fuel level sensor (sending unit):An owner reports dealers replacing fuel pumps without fixing the light; confirm the signal first; labor varies; get a quote.
Labor varies by vehicle and shop; get a quote before you approve a repair.
Compare used part prices on PartPriceGuideOn your vehicle
ChryslerYour car
2007 · Pacifica
Supported by vehicle dataA 2007 owner reports the gauge dropping to zero with U1403 and a repeat after fuel pump replacement.
2008 · Sebring
Supported by vehicle dataA 2008 owner read U1403 as an implausible fuel level signal after cluster lights flashed and the car would not take a jump.
Related codes
No curated relationships for U1403 yet.
U1403 questions
Does U1403 mean the same on other makes?
Not necessarily. This page covers Chrysler only; we have not sourced meanings for other makes.
Sources and review
- NHTSA complaint ODI 11003841: 2007 Chrysler Pacifica
- U1403 Chrysler: Fuel level, serial communication - implausible signal
- NHTSA complaint ODI 11526510: 2008 Chrysler Sebring
- Last reviewed
- Written by
- Saurabh K.
- Editorial review
- Pending
- Technician review
- Technician review pending
This page explains what a code usually means; it is not a substitute for a professional inspection. How we source and review · Report an error