On Board Diagnostic Description

- The A/C control head -E87- (automatic climate control) and A/C clutch control module -J153- (manually controlled A/C) are equipped with Diagnostic Trouble Code (DTC) memory. If a malfunction occurs in a monitored sensor or component, a code is stored in the DTC RAM.
- Always check DTC memory as a first test step before attempting any repairs.
- Malfunctions which occur intermittently are sporadic, and are identified with an "SF" on the right side of the VAG 1551 Scan Tool (ST) display.
- The A/C control head -E87- (automatic climate control) distinguishes data between 19 different codes and stores malfunctions until DTC memory is erased (after checking) using VAG 1551 scan tool.
- The A/C clutch control module -J153- (manually controlled A/C) distinguishes data between 6 different codes and stores malfunctions only until ignition is switched off.
- OBD can only be performed using VAG 1551 scan tool in "Rapid data transfer" operating mode 1.
- Data Output via VAG 1551 scan tool is only possible with the ignition switched ON or engine running below 4000 RPM. At higher engine speeds (RPM), data output is interrupted.
- OBD includes storing, checking, erasing, and output Diagnostic Test Mode (DTM), but also offers additional uses with basic setting, control module identification and coding.
- Operating mode 2 (Blink Code Output) cannot be used for A/C/heating electronics diagnosis. Operating modes 3 (Self-Test) and 4 (dealership Identification) apply only to the scan tool and are described in the operating instructions of VAG 1551 scan tool.
- If a malfunction condition exists for longer than a certain time, the malfunction is stored as static. If the condition is no longer present for a certain time, the malfunction is identified as sporadic. This process is constantly repeated.
- The conversion of a malfunction from static to sporadic only occurs if the malfunction no longer exists for a certain time.
- If a sporadic malfunction no longer occurs for a certain period of time, it is automatically cleared.