P1797 — 7 documented meanings by make

P1797 does not mean the same thing on every car — manufacturers reuse the number for different faults. 11 makes document it: Audi, Chrysler, Citroen, Ford, Jaguar, Kia, Mazda, Peugeot, SEAT, Skoda, Volkswagen. Find your make below.

P1797 on Audi, SEAT, Skoda, Volkswagen

On Audi, SEAT, Skoda, Volkswagen vehicles P1797 is documented as: Vehicle speed signal, short circuit to positive. P1797 is stored when the ECU sees short to positive on vehicle speed signal. That describes how the circuit is behaving, not which part has failed — the wiring, the connector and the component itself can all produce it, which is why the checks below start with the cheapest.

Usually one of: Signal wire touching a permanently live wire in a damaged loom; Connector pins bridged by corrosion or a bent terminal; Internal fault in the component shorting the signal to supply; Incorrect wiring after an aftermarket accessory was fitted.

Check first, cheapest first:

1. Disconnect the component and check whether the signal line still reads battery voltage
2. Inspect the loom for melted or rubbed insulation, especially near heat sources
3. Check the connector for a pushed-back or bent terminal
4. Trace the signal wire back to the module, looking for a live wire running alongside
5. Repair the harness, or replace the component if it is shorting internally

Related Audi, SEAT, Skoda, Volkswagen codes:

P1797 on Chrysler

On Chrysler vehicles P1797 is documented as: Manual shift overheat. P1797 points at transmission. The standard definition names the system involved; which part inside it has actually failed is what the checks below establish, cheapest first.

Related Chrysler codes:

P1797 on Citroen, Ford

On Citroen, Ford vehicles P1797 is documented as: Neutral switch circuit.

Related Citroen, Ford codes:

P1797 on Jaguar

On Jaguar vehicles P1797 is documented as: CAN TCM/ECM circuit. P1797 points at control module. The standard definition names the system involved; which part inside it has actually failed is what the checks below establish, cheapest first.

Related Jaguar codes:

P1797 on Kia

On Kia vehicles P1797 is documented as: P or N range signal or clutch pedal position switch, open or short circuit. P1797 is stored when the ECU sees open circuit on transmission. That describes how the circuit is behaving, not which part has failed — the wiring, the connector and the component itself can all produce it, which is why the checks below start with the cheapest.

Usually one of: Broken wire, most often at a flex point such as a door hinge or engine mount; Corroded or pushed-back terminal in the connector; Blown fuse on the supply side; Component failed with an internally open winding or element.

Check first, cheapest first:

1. Check the relevant fuse first — it is the cheapest thing that produces this code
2. Unplug and inspect both halves of the connector for corrosion and terminal fit
3. Continuity-test the wire end to end while flexing the loom by hand
4. Measure the component itself against its specification
5. Repair the break or replace the component, whichever the measurement points to

Related Kia codes:

P1797 on Mazda

On Mazda vehicles P1797 is documented as: CAN power train control module, PCM circuit, clutch pedal position switch/neutral switch circuit. P1797 points at transmission. The standard definition names the system involved; which part inside it has actually failed is what the checks below establish, cheapest first.

Related Mazda codes:

P1797 on Peugeot

On Peugeot vehicles P1797 is documented as: Barometer Pressure Circuit Malfunction. P1797 is stored when the ECU sees malfunction on the circuit named in the code. That describes how the circuit is behaving, not which part has failed — the wiring, the connector and the component itself can all produce it, which is why the checks below start with the cheapest.

Usually one of: Wiring or connector fault in the circuit; Component failed electrically; Supply or ground problem feeding the circuit; Controlling module fault, though this is the least common of the four.

Check first, cheapest first:

1. Read all stored codes — a general fault code is often the symptom of a more specific one
2. Inspect the connector and wiring for the named component
3. Check supply and ground at the component
4. Measure the component against specification
5. Replace the component once wiring and supply are ruled out

Related Peugeot codes:

Which one is yours

A generic OBD reader gives you the number, not which of these meanings your manufacturer assigned to it. To get to the specific one:

1. Use a brand-specific scanner — VCDS for VAG, INPA or ISTA for BMW, XENTRY for Mercedes, Forscan for Ford. It shows the manufacturer's own text rather than the generic one.
2. Read all stored codes together — the neighbouring ones usually point at which system is involved and narrow the list.
3. Check freeze-frame data: the RPM, temperature and load at the moment it triggered indicate which system was active.
4. If you have no brand scanner, tell me the make and model below and I will tell you which of these applies to your car.

Code family

P1xxx is manufacturer-specific code (VW/Audi, BMW, Mercedes, Toyota etc. have different meanings for the same code number).

Severity

Manufacturer-specific codes need a brand scanner (VCDS for VAG, INPA for BMW, STAR for Mercedes).

That is what holds for P1797 in general. From here it depends on your engine — tell me which car it is and what it does, and I will give you the steps for it: real procedures, torque figures and diagrams instead of general advice.