U0418
NetworkInvalid Data Received From Brake System Control Module
This usually starts out as a wiring or connector chase rather than a new brake module, which is the part most people fear. The fault is a network problem: the ABS/ESP module is putting out data that other modules on the CAN bus can't read properly, so the car flags it and starts shutting down safety functions. It's almost always caused by corrosion, a dodgy connector, or a power/ground issue rather than a dead module, but you need the right kit to prove which one. Until it's sorted, expect the ABS and stability control to drop out.
ⓘ Information only. This page provides general educational information about fault code U0418. We do not assess the urgency or safety implications of any specific fault. That requires in-person diagnosis by a qualified mechanic. Full terms.
Recommended next steps
Whether a fault is urgent, drivable, or routine depends entirely on the cause on a specific vehicle, and that can only be determined by a qualified mechanic with diagnostic equipment. If a warning light is illuminated, the most reliable next step is professional diagnosis.
What does U0418 mean?
U0418 is a Network (CAN bus, module communications) fault code. It indicates: Invalid Data Received From Brake System Control Module.
This is a standardised OBD-II code. The technical definition is the same regardless of the make or model of vehicle, although specific causes and symptoms can vary between vehicles.
Symptoms commonly associated with this code
Symptoms that drivers often report alongside this code. Not all may apply to every case:
- • ABS and ESP/traction warning lamps lit on the dash, sometimes together with a brake warning
- • Stability and traction control switching off, often coming and going on rough roads
- • Driver-assist features throwing 'unavailable' messages (lane keep, adaptive cruise, hill hold)
- • Pedal can feel slightly different if ABS support is lost, though normal hydraulic braking remains
- • Longer stopping distances on slippery surfaces because ABS isn't intervening
- • On some cars the engine light joins in as the fault ripples across the bus
Possible causes
Causes commonly associated with U0418, listed in approximate order of typical investigation. The actual cause on a specific vehicle can only be confirmed by professional diagnosis.
- 1. Corroded or water-damaged connectors at the ABS pump, the usual offender. Salt and road spray get into the multiplug and rot the pins
- 2. Chafed or broken wiring in the CAN high/low pair, often where the loom flexes near a wheel arch or runs along the subframe
- 3. Poor earth or ground point feeding the module, giving dirty signal voltage
- 4. Voltage supply trouble, a tired battery or alternator spiking and dropping enough to upset the module mid-drive
- 5. ABS/ESP module itself faulty or with corrupted software, less common but it does happen, particularly after a flat-battery jump start
- 6. A wheel speed sensor sending nonsense that the module can't reconcile, then it reports invalid data upstream
- 7. A wider CAN bus fault where another module on the network is dragging the bus down
How mechanics typically diagnose
A typical diagnostic sequence used by mechanics, provided here for educational reference only. Diagnostic work should be performed by a qualified mechanic with the appropriate tools and training.
- 1. Scan every module with a CAN-capable tool, not just a basic code reader, and write down all the U-codes and any C-codes. If three or four modules all report comms loss, you're chasing a bus or power problem, not the ABS module
- 2. Pull the ABS pump connector and inspect it properly. Look for green corrosion, bent or pushed-back pins, and moisture. This is where a lot of these end
- 3. Check the module's power feed and earth. You want a steady supply around 11.5-13.5V with the engine running, and a clean ground with under an ohm to the body
- 4. Probe the CAN high and low lines for the correct resting voltages and roughly 60 ohms across the pair with the ignition off. A reading way off that points to a wiring break or a shorted module
- 5. Watch the live data from the ABS module while you wiggle the loom near the arches and pump. If messages drop out as you flex it, you've found your broken wire
- 6. Only if power, ground, and wiring all check out should you look at module software or a replacement. Reprogram before condemning the hardware
Common questions about U0418
How do I work out whether it's the wiring or an actual dead module? +
Start with the connector at the ABS pump and the module's power and earth, because that's where the cheap fixes live. If you find corrosion, damaged pins, or moisture in the plug, clean it, treat it, and recheck before spending a penny on parts. Then flex the loom around the wheel arches while watching live data, a wire that's broken under the insulation will make the fault flicker. A module is only the likely answer if the connector is clean, the supply is steady at 11.5-13.5V, the earth is solid, and the CAN lines measure correctly. Plenty of these turn out to be a £20 pin repair, not a £600 module.
Can I clean the connectors and sort this myself? +
Cleaning a corroded connector is well within reach for a confident DIYer. Disconnect the battery first, unplug the multiplug at the ABS pump, and check for green muck, water, and pins that have backed out. Clean with contact cleaner, dry it, and a smear of dielectric grease helps keep water out next time. That alone fixes a fair number of these. What you can't realistically do at home is chase a CAN bus break or reflash the module, that needs proper diagnostic gear and is where you'll want a garage or auto-electrician.
Will clearing the code make it stay gone? +
If the cause is still there, no. Clear it and it'll come back within a drive or two, sometimes within minutes if it's a hard fault. Intermittent ones are sneakier, a loose connector or a wire that only breaks contact over a bump can let the code vanish for days before returning. That's not the car healing itself, it's the fault hiding. Don't trust a cleared code as a fix. Find what caused it, repair that, and then clearing it actually means something.
Information only, not professional advice
The information on this page is provided for general guidance and educational purposes only. It is not a substitute for diagnosis or repair advice from a qualified mechanic. Always verify any fault before paying for repairs. carfaultcodes.co.uk accepts no liability for decisions made based on this information. Full terms →