P03C1 Cylinder 5 Pressure Sensor Circuit Intermittent/Erratic

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. P03C1 means the sensor signal is erratic or drops out for moments – typically a loose contact at the glow plug connector, a chafed harness or sensor electronics unstable with temperature. The only manufacturer we found using this code family, GM's European 2.0 CDTI four-cylinder diesel (Saab 9-5, 2010), uses it for cylinders 1 to 4 as 'circuit erratic': signal outside its range for more than 0.2 s with the engine running. 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 code often comes and goes.

Likely causes

Symptoms

• Check engine light on
• Occasionally rough running
• Often no symptoms, the code comes and goes

Repair estimate

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

Related codes

References: law.cornell.edu, saabwisonline.com, borgwarner.com.