C1028

What the Code Means

Code C1028 points to a fault in the master cylinder pressure sensor — the brake pressure sensor mounted inside the ABS pump. The sensor measures the pressure the driver applies to the pedal and sends that data to the control module, which uses it to calculate ABS and DSC interventions.

The fault is common on ATE MK60 brake systems, where this sensor is built into the pump module and is a statistically weak point in the design.

Symptoms

Indication:

• ABS and DSC warning lights come on in the instrument cluster;
• the brake pressure sensor fault is stored in the module memory.

Diagnosis and Repair

1. Run a fault code scan and confirm that C1028 is present in the ABS/DSC module memory.
2. Check the sensor readings in live data: make sure the pressure changes appropriately when you press the brake pedal.
3. If the sensor fault is confirmed, replace or rebuild the ABS pump: on ATE MK60 systems the sensor is part of the module and isn't serviced separately.
4. After restoring the pump, bleed the brake system.
5. Clear the codes and confirm the error doesn't return.

Secondary Problems

• Loss of stability control: without reliable pressure data, DSC and ABS can't intervene in braking correctly.
• Unsafe braking: in an emergency, stopping effectiveness and stability drop, which makes driving the car risky until the fault is fixed.