P03BD: Cylinder 5 Pressure Sensor Circuit

What does P03BD mean?

Some diesels have a combustion pressure sensor in the glow plug; the engine module uses it to control injection for each cylinder. This code concerns cylinder 5. P03BD is the general circuit code for this pressure sensor, meant for modules that do not separate open circuits and shorts into low and high. The only manufacturer we found using this code family, GM's European 2.0 CDTI four-cylinder diesel (Saab 9-5), splits such faults into low and high codes for cylinders 1 to 4, and VW's US 2.0 TDI engines with pressure-sensing glow plugs use their own codes (P13CE ff). For cylinder 5, which only engines with at least 5 cylinders have, no manufacturer document available to us uses the code; the description follows that logic and CARB. The sensor has three wires (5 V reference, ground, signal); without it the module drops combustion control for that cylinder.

The code tells you which monitor failed, not which part is broken. Test before replacing parts.

Symptoms

• Check engine light on (often after two trips)
• Usually barely noticeable – combustion control for the cylinder is switched off
• Possibly rougher running, more noise or slightly higher consumption

Common causes

• High Connector at the pressure-sensing glow plug loose or corroded
• Medium Reference, signal or ground wire open or shorted
• Medium Sensor electronics in the glow plug faulty
• Low Engine module (reference voltage or input)

Likelihood is a general estimate across vehicles; your make and model may differ.