C1851 Citroen C5 Diagnostic Trouble Code

C1851 Citroen C5 code definition:
C1851 is a kind of OBD-II Diagnostic C-Chassis Diagnostic Trouble Code for Citroen C5.

C1851 Citroen C5 is triggered when the bank 1 camshaft position sensor doesn't match the signal from the crankshaft position sensor. This is because the barometric pressure sensor is part of the MAF sensor. Sometimes, the MAF's sensing wire can accumulate and get covered with dirt, dust and/or oil residue, which can also lead to the error code.

Symptoms

Symptoms of a C1851 Citroen C5 diagnostic trouble code may include:

Blown fuse (if applicable)
Engine surge
Reduction in engine performance, especially at low RPM levels
Poor fuel economy

Possible Causes :

Rarely - faulty Powertrain Control Module (PCM-programming required after replacement)
Rough running engine due to misfiring plugs. Many engines have misfire codes to indicate the cylinder effected, such as P0307 for number 7.
Dirty air cleaner element Damaged DPF

Common Misdiagnoses

TP Sensor Learn Not Complete Problem
Low Coolant Circuit Problem
Cruise Control System - Vehicle Accel Too High Problem
TFP Valve Position Switch-Drive Without Drive Ratio Problem
Problem

Repair Processes :

Look for missing ground strap or a rusty ground where the fuel tank is grounded to the frame. Check for damage to the wiring harness connector. Now, clear the codes and test-drive the vehicle to see if the code is reset. Replace the oxygen sensor that is downstream from the catalytic converter on the side of the engine that does not contain cylinder #1. Also, if a oxygen sensor code stating "heater circuit malfunction" the sensor has most probably failed.

Process Tips

Diagnostic trouble code C1851 Citroen C5 is not difficult to diagnose and repair. Thus, it always pays to have a qualified technician to look after your vehicle should this error code arise.

Diagnosing this code requires the engine to be in good running shape, without unmetered air entering the engine. If other codes that relates to misfiring condition, lean running or air entering the engine is present, then you must first fix those error codes before C1851 Citroen C5.

Fortunately, C1851 Citroen C5 is a fairly common OBD code, meaning that it applies to all makes and models of vehicles made after 1996.