4200A3

What the Code Means

Code 4200A3 indicates an open circuit in the hydraulic impulse accumulator (HIS) solenoid valve. This valve damps pressure spikes in the automatic transmission hydraulic system. The open circuit usually comes from chafed wiring in the area of connector X13, which breaks electrical continuity.

Symptoms

• Transmission warning light on
• Harsh shifts
• Possible limp mode

Diagnosis and Repair

Step 1: Inspect the Wiring Harness

Check the wiring harness around connector X13 for chafing or damage.

Step 2: Repair or Replace the Harness

If you find damage, repair or replace the harness.

Step 3: Check Solenoid Resistance

Measure solenoid resistance — nominal value: 4–6 ohms.

Step 4: Replace the Solenoid

If resistance is out of spec, replace the solenoid valve.

Secondary Damage

Driving with an open circuit can cause unstable transmission operation and accelerated clutch pack wear from unregulated pressure spikes.