A 2013 Honda Civic diesel owner came in with P16CD (No. 1 Glow Plug Circuit Open) and P049B (Exhaust Gas Recirculation B Flow Insufficient Detected) codes. The car was running rough, especially on acceleration, and he needed help knowing where to begin.

I suspected the last code, P049B, was the one giving the poor acceleration. It refers to the EGR valve and indicates insufficient flow. The details on the other code refer to the glow plug circuit (P16CD) and although these issues also needed addressing, the EGR valve was the one I was going to start with.

To begin, I was going to read the codes myself, just to ensure that I was not chasing my tail looking for problems with the incorrect information. I did check the codes, and these were correct.

The EGR valve on this engine is very accessible and easily removed and cleaned, so this was my first step. After a good clean of the EGR valve, it was refitted and then I moved onto the glow plug code.

Checking the continuity of the glow plug circuit, I found it was a poor connection on the glow plug terminal that was causing the code to appear.

With this glow plug connection rectified, and the EGR clean, I started up the engine. During a good test drive, I was pleased to see that the Check Engine stayed off.

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