P1788 Diagnostic Trouble Code

P1788 is a kind of OBD-II Diagnostic P-Powertrain Diagnostic Trouble Code.

It is considered generic because it applies to all makes and models of vehicles, although specific repair steps may be different depending on your car model.

Symptoms

Symptoms of a P1788 diagnostic trouble code may include:

The light may stay on or light intermittently as the DPF regenerates. The engine will be sluggish on acceleration.
Faulty PCM
If the DPF is not cleared the ECU will revert to the "Limp Home Mode" until the situation is corrected
Hesitation upon acceleration

Possible Causes :

Some aftermarket accessories and performance modifications
A faulty oxygen sensor. This will set a code in itself, however, a faulty oxygen sensor does not automatically condemn the sensor. The code just means that the sensor signal was not within specifications. An air leak or any of the above will cause an erroneous signal. There is a multitude of O2 codes relating to O2 performance which gives a clue to the problematic area.
An air leak forward of the DPF will change the sensor readings resulting in the code

Repair Processes :

With the valve disconnected, the red voltmeter lead should be attached to the IMRC valve power wire and the black voltmeter lead connected to ground. Pack the connector cavity with dielectric silicone compound (same stuff they use for light bulb sockets and spark plug wires) and reassemble.

Process Tips

Diagnostic trouble code P1788 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 P1788.

Fortunately, P1788 is a fairly common OBD code, meaning that it applies to all makes and models of vehicles made after 1996.

P1788 Trouble Code For Specific Cars

P1788 Durkopp 16 Hp Immobilizer Code Word/ID Number Write Failure
P1788 Jeep Dakar Seat Driver Rear Up Switch Circuit Open
P1788 Saturn Sky Incorrect Module Configuration
P1788 Irmscher Tigra SCP (J1850) Invalid or Missing Data for Non-Legislated Diagnostics
P1788 Opel Admiral Damper RF Circuit Open
P1788 Jeep Patriot Seat Driver Recline Backward Circuit Failure
P1788 Marendaz 13 Transmission 4-Wheel Drive Low Indicator Circuit Failure