An OBD2 scanner can’t directly detect a blown head gasket. However, it can detect symptoms related to a blown head gasket that may trigger diagnostic trouble codes (DTCs). These codes can provide clues that point towards a potential head gasket issue. For example, a misfire due to coolant leaking into the cylinders might trigger a P0300 code (random/multiple cylinder misfire). Similarly, a rich or lean condition caused by combustion gases entering the cooling system could trigger codes like P0171 (system too lean) or P0172 (system too rich).
A blown head gasket can manifest in various ways, making diagnosis challenging. One common symptom is coolant mixing with engine oil, creating a milky substance. This contamination usually isn’t directly detectable by an OBD2 scanner. However, if the oil contamination affects the engine’s performance and triggers a misfire, the OBD2 scanner will likely register a related code. Another sign is excessive white smoke from the exhaust, indicating coolant burning in the combustion chamber. While an OBD2 scanner won’t detect the smoke itself, consequential issues like a misfire will trigger relevant codes.
Furthermore, a blown head gasket can lead to combustion gases leaking into the cooling system. This can cause the cooling system to over-pressurize and potentially lead to overheating. While the OBD2 system might not directly detect the leak, it could register a P0128 code (thermostat malfunction) if the engine struggles to maintain the correct operating temperature. In some cases, an OBD2 reader might show a P0335 code, like in the case mentioned where the crankshaft position sensor signal was not detected. This particular code doesn’t directly indicate a head gasket problem but highlights the importance of comprehensive diagnostics. It’s crucial to remember that a P0335 code relates to a faulty crankshaft position sensor and requires separate investigation.
Addressing a potential head gasket issue requires a multi-faceted approach. Start by using an OBD2 scanner to check for any DTCs. Then, inspect the engine oil and coolant for signs of contamination. Look for excessive white smoke from the exhaust and check the cooling system for pressure leaks. If you suspect a blown head gasket, performing a compression test or a leak-down test can provide a more definitive diagnosis. As seen in the example, flushing the cooling system with a distilled water and vinegar solution can help remove contaminants and might temporarily alleviate some symptoms, but it won’t fix a blown head gasket.
In conclusion, while an OBD2 scanner cannot definitively diagnose a blown head gasket, it serves as a valuable tool in identifying related symptoms. Combining OBD2 data with a thorough visual inspection and further testing is crucial for accurate diagnosis and repair. Relying solely on an OBD2 scanner for this complex issue is insufficient.
