B1819

Wiper Rear Motor Up Relay Coil Circuit Open

Body Chassis/Safety Wiper Control System 🟢 Low — Fix at next service ✅ Safe to Drive
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What This Actually Means

In plain language — no jargon

The electrical coil in the rear wiper motor's up-direction relay has an open circuit, meaning electricity can't flow through it properly. It's like a broken switch that prevents the relay from engaging to move the rear wiper blade upward.

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Symptoms You May Notice

3 known symptoms for this code
Rear wiper fails to move to up/park position
Rear wiper stuck in middle or down position
No audible relay click when wiper control activated
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How Your ECU Detects This

Technical sensor logic and voltage thresholds

The ECU monitors coil current draw when commanding the rear wiper motor upward. It detects an open circuit when coil resistance exceeds expected threshold, indicating a break in the wiring or relay coil windings. The fault sets when no current flows despite voltage being applied to the relay circuit.

Voltage & Parameter Thresholds

ParameterNormal RangeFault Condition
Rear Wiper Up Relay Coil Current 0.5-2.0 Amps Below 0.05 Amps or no current detected
Coil Resistance 6-12 Ohms Above 100 Ohms or open circuit (infinite resistance)
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Diagnostic & DIY Fix Guide

Check these in order — from cheapest to most complex
1
Wiper relay connector
Inspect and reseat the relay connector at the fuse/relay box to ensure good contact.
2
Rear wiper motor relay
Replace the relay with an OEM or equivalent part if connector check fails.
3
Wiring harness
Check for broken or corroded wires between relay and motor; repair or replace damaged sections.
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When to See a Professional Mechanic

Not all fault codes are safe to DIY

Code B1819 is a low-severity fault. Your vehicle is generally safe to drive to a workshop for diagnosis. However, do not ignore it indefinitely — low-severity codes often indicate developing problems that become expensive if neglected. Book a diagnostic appointment within 2–4 weeks. If you notice any additional symptoms (rough running, power loss, unusual smells), treat it as higher priority.

Safety note: OBD-II codes identify the system or circuit where a fault was detected — they do not always identify the exact failed component. A professional mechanic using live sensor data will diagnose the root cause more accurately than replacing parts based on the code alone.
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How to Clear Code B1819

What happens after you fix the fault

Once the fault is repaired, B1819 can be cleared using any OBD-II scanner. Connect the scanner, navigate to "Clear Codes" or "Erase DTCs," and confirm. The check engine light turns off immediately.

The code will return if the root cause was not actually fixed. The ECM re-detects the fault within 1–3 drive cycles and sets the code again.

✅ Safe to Clear When
  • Fault has been diagnosed and repaired
  • You want to confirm the repair worked
  • Code appeared after a sensor was cleaned
⚠️ Do Not Clear When
  • Preparing for an emissions/PUC test
  • Root cause is still undiagnosed
  • Check engine light is flashing
Emissions test note: Clearing codes resets OBD readiness monitors. Most vehicles need 50–100 km of mixed driving before monitors complete. Do not clear codes immediately before an emissions or PUC inspection.