Invalid Data Received From ECM/PCM "A"

What it means

Another module is receiving data from the engine computer, but the data is invalid. This usually happens because the engine computer itself has a fault code that makes some of its data unusable.

Symptoms

• Warning lights in other systems (ABS, transmission)

Probable causes

Most likely first

1. 1A fault stored in the engine computer
2. 2Software mismatch after a module replacement
3. 3Network wiring problem

How to diagnose it

Work through these in order before buying parts

1. 1Read and repair any codes in the engine computer first; this code often clears by itself afterwards.
2. 2Check the battery and charging voltage. Low voltage is the most common cause of communication codes.
3. 3Scan all modules: if one module is missing from the list, focus on its power, ground and connectors.
4. 4Check the fuses that feed the module that is not communicating.
5. 5With the battery disconnected, measure resistance between CAN High and CAN Low at the diagnostic port; about 60 Ω is normal.
6. 6Check for technical service bulletins (TSBs) or software updates for your make and model; some codes have known factory fixes.

Common fixes

• Repair the engine computer fault
• Update module software