Cause
Poor sensor ground connection
The sensor's own earth, as distinct from the module's. A sensor referenced to a poor ground reports a consistent offset rather than an obvious fault, so the reading looks credible and is wrong by the amount the ground has shifted — which is why a rationality code appears while every circuit test passes.
Typically a moderate job.
Some of these codes mean you should stop driving
5 of the 16 codes this can cause indicate a fault where continuing to drive risks damage or is unsafe. Which one you have matters more than the cause does — read the code's own page before deciding.
Codes this can cause (16)
Codes where this is a likely explanation first, rather than merely a possible one.
- P052F Glow Plug Control Module 1 System Voltage Likely for this code Moderate
- P060C Internal Control Module Main Processor Performance Likely for this code Stop driving High
- P2135 Throttle/Pedal Position Sensor/Switch A/B Voltage Correlation Likely for this code Stop driving High
- P21CC Reductant Control Module Supply Voltage High Likely for this code Moderate
- P016A Excessive Time To Enter Closed Loop Air/Fuel Ratio Control Moderate
- P05F8 Reductant Heater Control Module Performance Moderate
- P064C Glow Plug Control Module 1 Moderate
- P066E Cylinder 3 Glow Plug Control Circuit Low Moderate
- P068A Engine Control Module Power Relay De-Energized Performance — Too Early High
- P06BD Cylinder 5 Glow Plug Circuit Range/Performance Moderate
- P2136 Throttle/Pedal Position Sensor/Switch A/C Voltage Correlation Stop driving High
- P2137 Throttle/Pedal Position Sensor/Switch B/C Voltage Correlation Stop driving High
- P2139 Throttle/Pedal Position Sensor/Switch D/F Voltage Correlation Stop driving High
- P2185 Engine Coolant Temperature Sensor 2 Circuit High Moderate
- P2186 Engine Coolant Temperature Sensor 2 Circuit Intermittent/Erratic Moderate
- P24D1 Particulate Matter Sensor Regeneration Incomplete Moderate
Information, not instruction
CarGeek is a reference, not a service manual. Its pages are written from public sources and from what other people have found, never from a manufacturer's own service information, so they can be wrong or incomplete for your particular vehicle. Some of what they describe carries real risk: high voltage, fuel under pressure, stored energy, hot and moving parts.
Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
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