Ford U1900 Code: CAN Communication Bus Fault – Receive Error
A Ford module stopped receiving messages it expects from another module on the CAN network.
At a glance
Severity: Moderate
- Meaning
- CAN Communication Bus Fault – Receive Error
- System
- Module Communication · Network
- Safe to drive?
- With caution
- Typical repair cost
- $0–$1,200
- DIY difficulty
- Moderate
U1900 is Ford's older-format network code, used on many vehicles built before the switch to the U0xxx lost-communication codes. The module that stores it is saying that one or more CAN messages it depends on did not arrive; for example, on F-150 and Super Duty trucks of the mid-2000s the PCM logs U1900 when it misses messages from the instrument cluster, ABS module or integrated trailer brake controller, and on the Five Hundred, Freestyle and Focus it can appear in the airbag, steering or cluster modules. U1900 therefore doesn't name the faulty part by itself: you have to see which modules store it and which module stopped talking. A single U1900 left over after a dead battery or jump start is common and harmless, while one that keeps coming back usually traces to low voltage, a failing instrument cluster or a wiring fault on the CAN pair.
Can I keep driving? If it's a one-time stored code and everything works, driving is fine. If warning lights, gauges or the transmission act up, or the engine stalls, have it diagnosed promptly, because modules may be running on default values.
How to read U1900
- U Network
- 1 Manufacturer-specific
- 9 Module Communication
- 00 Specific fault
Symptoms
- Several warning lights at once (ABS, airbag, check engine, traction)
- Gauges dropping to zero or the instrument cluster going blank intermittently
- Harsh shifting or a limp-like mode when the PCM loses cluster or ABS data
- Trailer brake controller message or inoperative trailer brakes on equipped trucks
- No symptoms at all when U1900 is only a stored history code
Possible causes
Ranked by how often each cause is behind this code (editorial estimate).
- Low or unstable battery voltage, including after a jump start or battery replacement
- Instrument cluster with cracked solder joints dropping off the network (known on several Ford generations)
- Corroded, loose or water-damaged connector on a module or at an inline CAN splice
- Chafed, shorted or open CAN-high/CAN-low wire
- Aftermarket device (remote start, trailer brake controller, OBD dongle) disturbing the bus
- Internal failure of the module that stopped transmitting
Diagnosis step by step
Run a full network scan
Read every module and note which ones store U1900 and which ones don't respond at all. The module that is missing from the list, or the one all the others complain about, is where to focus.
Tools: OBD-II scanner
Rule out voltage problems
Test the battery and charging system; resting voltage around 12.6 V and 13.8 to 14.8 V running. Clear the codes and see whether U1900 returns once voltage is stable.
Tools: Multimeter
Measure bus resistance at the DLC
With the battery disconnected, measure between pins 6 and 14 of the diagnostic connector. About 60 ohms means both terminating resistors are present; about 120 ohms means one end of the bus is open, and near zero means CAN-high and CAN-low are shorted together.
Tools: Multimeter
Check bus voltages
With the key on, CAN-high should read roughly 2.5 to 3.5 V and CAN-low roughly 1.5 to 2.5 V to ground. A line stuck at 0 V or at battery voltage points to a short to ground or power.
Tools: Multimeter
Isolate modules one at a time
If the bus looks shorted, unplug modules one at a time (with the key off) while watching resistance or voltage. The reading returning to normal identifies the module or branch that is dragging the bus down.
Tools: Multimeter, Screwdriver
Check the instrument cluster and connectors
If gauges flicker or drop out together with U1900, the cluster is the prime suspect. Inspect its connector and those of the PCM and ABS module for corrosion or loose terminals before replacing anything.
Tools: Flashlight, Screwdriver
Where the parts are
- 1Battery
- 2Alternator
- 3Engine computer (ECM)
- 4CAN bus
- 5Transmission
- 6Wheel speed sensor
- 7High-voltage battery
Repair options & costs
| Repair | DIY? | Estimated cost |
|---|---|---|
| Battery / charging repair and code clear | Yes | $0–$320 |
| Clean or repair module connectors | No | $60–$250 |
| CAN wiring diagnosis and repair | No | $150–$500 |
| Instrument cluster repair (mail-in or specialist) | No | $150–$400 |
| Replace and program a failed module | No | $400–$1,200 |
Rough US estimates for parts and labor; shop rates vary by region. Not a quote.
Emissions / smog test impact
Depends
A stored U1900 alone won't fail a US smog check, but if the module losing data turns on the check engine light, or the PCM reports not-ready monitors after the fault, the vehicle can fail until it's repaired and driven.
Frequently asked questions
Which module is actually bad when I see U1900?
U1900 is recorded by the module that stopped receiving messages, not the one that failed to send them. Compare which modules store it and which don't answer the scan tool to find the silent one.
Is U1900 serious if everything seems to work?
A single stored U1900 after a battery change or jump start is often harmless. Clear it and see whether it returns; if it does, look for voltage or wiring problems before they cause symptoms.
Why does my speedometer drop out with U1900?
The cluster gets vehicle speed and other data over CAN. When messages are lost, or the cluster itself has cracked solder joints, the needles can fall to zero until communication recovers.
Why do newer Fords never show U1900?
Later Ford generations report network faults with the standard U0xxx lost-communication codes, which name the missing module directly, such as U0100 for the PCM or U0121 for the ABS module.
Sources
- Manufacturer public service information (cross-checked)
- Methodology: How We Build Code Pages · Data Sources We Use · Editorial Policy