Fault Code Library
Practical guides to common fault codes: what they mean, what can cause them and what should be checked before replacing or repairing a module.
C110702 – Video line for image processing: signal fault (Audi & VW front camera)
What C110702 / 0161 “No camera found on startup” means on Audi A6, A7, A8 and VW Touareg, how to find the cause and how the front camera is repaired.
Read guide →Latest fault guides
U0100 – Lost communication with ECM/PCM
U0100 is a generic network code: another module stopped receiving messages from the engine control module. Causes, checks and when the engine...
Read guide →
U0140 – Lost communication with body control module
U0140 is a generic network code: another module stopped receiving messages from the body control module. Causes, checks and when the body...
Read guide →
U0131 – Lost communication with power steering control module
U0131 is a generic network code: another module stopped receiving messages from the power steering control module. Causes, checks and when the...
Read guide →
U0101 – Lost communication with TCM
U0101 is a generic network code: another module stopped receiving messages from the transmission control module. Causes, checks and when the transmission...
Read guide →
U0155 – Lost communication with instrument panel cluster
U0155 is a generic network code: another module stopped receiving messages from the instrument cluster. Causes, checks and when the instrument cluster...
Read guide →
U0121 – Lost communication with ABS control module
U0121 means another module stopped receiving messages from the ABS control module on the vehicle network. Causes, checks and when the ABS...
Read guide →
P20EE SCR NOx Catalyst Efficiency Fault (AdBlue): Causes and Diagnosis
What P20EE means, which AdBlue/SCR components to check first, and the documented Peugeot Boxer III software case.
Read guide →
P0606 ECU / PCM Processor Fault: Causes, Diagnosis and When the ECU Is Really Faulty
What P0606 means, why it does not always mean a failed ECU, and what to check before repair or replacement.
Read guide →
Vauxhall Corsa D C0545 Power Steering Torque Sensor Fault: Causes and Diagnosis
What C0545 means on the Vauxhall Corsa D electric power steering, typical symptoms and why the EPS column version must be identified...
Read guide →
VAG 01435 Brake Pressure Sensor 1 (G201): Causes and Diagnosis
What VAG fault 01435 (G201) means, why it can be a basic setting, brake switch, sensor or hydraulic issue, and what to...
Read guide →
Ford U1900 CAN Communication Bus Fault on the Focus Mk2: Causes and Diagnosis
What Ford U1900 means on the Focus Mk2, why it is not automatically a faulty instrument cluster, and what a technician should...
Read guide →Send the code, vehicle and symptoms – we tell you what to check first.