← Back to list

P2135 Fault in 2003 Mazda 6 V6 Only Occurs When Engine is Cold - Vacuum System Inquiry

Model: 2003 Mazda 6 V6 Fault Code: P2135 Posted: 2014-06-25 10:20

I'm experiencing a recurring P2135 fault in my 2003 Mazda 6 V6, which only appears when the engine is cold. The issue causes the engine RPM to drop unexpectedly—though I don't remember the exact code that triggered this, it reappeared after the engine cooled down later today. After replacing spark plugs and addressing a faulty coil, the P2130 code became more frequent. Upon inspection, I found a torn vacuum hose between the air filter and throttle body, which connects to the valve cover. Replacing this hose resolved some symptoms, but the original P2135 issue persists. My question is: How does the engine control module simulate an auto-choke function during cold starts? Is there a specific vacuum line or component—other than the throttle body—that may need replacement or repair to resolve this? Thanks for any insights on the vacuum system's role in cold-start performance and how it interacts with the P2135 code.

Related fault codes

P2135

Comments (3)

Anonymous 2014-06-25 11:12

Have you already checked official resources for P2135?\nhttp://www.obd-codes.com/p2135

Anonymous 2014-06-25 19:37

Yes, I've reviewed the post and registered to ask my question. While I understand that OBD-II codes only point to a general area of failure, I'm an electrical and instrumentation technician with over 30 years of experience. I’m familiar with voltage differences between sensors for just two seconds—however, I believe there may be other underlying reasons why the throttle position sensor (TPS) and accelerator position sensor (APS) show different voltages beyond failed sensors, dirty throttle bodies, or electrical faults. My knowledge of automotive vacuum systems is limited, but I suspect a deeper issue in the vacuum circuit. Thank you for sharing details about the codes and related diagnostics.

Anonymous 2014-06-26 08:33

I’ll try to assist—what exactly are you asking about the vacuum system? Just theory or a specific component? Where does the suspected vacuum line connect? The throttle body is known to be a common issue in this model. Mazda has issued a Technical Service Bulletin (TSB) covering most affected units, recommending replacement. You can obtain a copy from your local Mazda dealer—Bulletin No: 01-016/06.