P1971 — 3 documented meanings by make

P1971 does not mean the same thing on every car — manufacturers reuse the number for different faults. 6 makes document it: Audi, Mitsubishi, Saab, SEAT, Skoda, Volkswagen. Find your make below.

P1971 on Audi, SEAT, Skoda, Volkswagen

On Audi, SEAT, Skoda, Volkswagen vehicles P1971 is documented as: Secondary air pump relay 4, J705, short circuit to positive. P1971 is stored when the ECU sees short to positive on secondary air injection. 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:

P1971 on Mitsubishi

On Mitsubishi vehicles P1971 is documented as: Fail-safe control monitoring.

Related Mitsubishi codes:

P1971 on Saab

On Saab vehicles P1971 is documented as: Unreliable data from TRIONIC.

Related Saab 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 P1971 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.