P1625 — 32 documented meanings by make

P1625 does not mean the same thing on every car — manufacturers reuse the number for different faults. 21 makes document it: Audi, BMW, Chevrolet (USA), Chrysler, Citroen, Ford, Honda, Hyundai, Isuzu, Kia, Mazda, Mercedes-Benz, Opel / Vauxhall, Peugeot, Saab, SEAT, Skoda, Suzuki, Toyota, Volkswagen, Volvo. Find your make below.

P1625 on Audi, SEAT, Skoda, Volkswagen

On Audi, SEAT, Skoda, Volkswagen vehicles P1625 is documented as: Drive train data bus, implausible message from gearbox control unit. P1625 is stored when the ECU sees range or performance 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: Sensor reading is inside its electrical range but does not match reality; Contamination or deposits changing what the sensor sees; A mechanical fault upstream that the sensor is correctly reporting; Sensor drifted with age without failing outright.

Check first, cheapest first:

1. Compare the live value against a second sensor or a known-good figure — this code is about plausibility, not a dead circuit
2. Look for the mechanical cause first: leaks, restrictions or wear that would genuinely produce this reading
3. Clean the sensor if it is the type that fouls
4. Check freeze-frame data to see under what conditions it triggered
5. Replace the sensor only after the mechanical side is ruled out

Related Audi, SEAT, Skoda, Volkswagen codes:

P1625 on BMW

On BMW vehicles P1625 is documented as: Pedal position sensor potentiometer supply channel 2 electrical. P1625 points at accelerator pedal sensor. The standard definition names the system involved; which part inside it has actually failed is what the checks below establish, cheapest first.

Related BMW codes:

P1625 on Chevrolet (USA)

On Chevrolet (USA) vehicles P1625 is documented as: TCM flash checksum fault (SATURN). P1625 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 Chevrolet (USA) codes:

P1625 on Chrysler

On Chrysler vehicles P1625 is documented as: Main relay.

Related Chrysler codes:

P1625 on Citroen, Peugeot

On Citroen, Peugeot vehicles P1625 is documented as: Safety faults; Incorrect ESP demand. P1625 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 Citroen, Peugeot codes:

P1625 on Ford

On Ford vehicles P1625 is documented as: Fan driver, open circuit to positive (VLCM). P1625 is stored when the ECU sees short to positive 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: 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 Ford codes:

P1625 on Honda

On Honda vehicles P1625 is documented as: Reference nr. 1 circuit, low voltage, APS1, mass air-flow sensor. P1625 is stored when the ECU sees signal too low 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: High resistance in the supply or ground path, dragging the signal down; Corroded connector adding resistance the module reads as a low reading; Sensor drifted out of tolerance with age; Partial short to ground somewhere in the signal line.

Check first, cheapest first:

1. Read the live value on a scanner and compare with a known-good reading
2. Clean and re-seat the connector, then re-test before replacing anything
3. Check the ground point for that circuit — a poor ground causes this far more often than a bad sensor
4. Measure the sensor against specification with the connector back-probed
5. Replace the sensor only once the wiring and ground have been ruled out

Related Honda codes:

P1625 on Hyundai

On Hyundai vehicles P1625 is documented as: Air-conditioning condenser fan relay, cooling fan relay, circuit high. P1625 is stored when the ECU sees signal too high on cooling system. 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: Open ground for the sensor, letting the signal float up; Signal line shorted to a supply voltage; Sensor failed open, which the module reads as maximum; Connector fault interrupting the return path.

Check first, cheapest first:

1. Read the live value and compare with what the conditions should produce
2. Check the sensor ground continuity back to the module
3. Unplug the sensor: if the reading changes, the wiring is intact and the sensor is suspect
4. Inspect the connector for corrosion or a spread terminal
5. Replace the sensor once ground and signal wiring are confirmed good

Related Hyundai codes:

P1625 on Isuzu

On Isuzu vehicles P1625 is documented as: PCM unexpected reset. P1625 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 Isuzu codes:

P1625 on Kia

On Kia vehicles P1625 is documented as: Radiator cooling fan circuit high, short circuit to positive. P1625 is stored when the ECU sees short to positive on cooling system. 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 Kia codes:

P1625 on Mazda

On Mazda vehicles P1625 is documented as: Fan circuit.

Related Mazda codes:

P1625 on Mercedes-Benz

On Mercedes-Benz vehicles P1625 is documented as: Check engine MIL.

Related Mercedes-Benz codes:

P1625 on Opel / Vauxhall

On Opel / Vauxhall vehicles P1625 is documented as: ECM/PCM system reset; Main relay stuck closed/open; Main relay opens too early/late; Main relay output, high/low voltage; CAN-BUS no communication with ABS/TC; Power supply relay, switched off too early/late; Internal power control final stage, open circuit; Internal power control final stage, high/low input. P1625 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 Opel / Vauxhall codes:

P1625 on Saab

On Saab vehicles P1625 is documented as: P-BUS; No BUS data from TCM; TCS/ESP missing on BUS; No BUS data from TC/ABS; No BUS data from TRIONIC; Main relay circuit, voltage drops to late; Main relay circuit, no voltage to control module; Main relay circuit, no voltage to control module pin 3.

Related Saab codes:

P1625 on Suzuki

On Suzuki vehicles P1625 is documented as: Immobiliser antenna. P1625 points at immobiliser / key. The standard definition names the system involved; which part inside it has actually failed is what the checks below establish, cheapest first.

Related Suzuki codes:

P1625 on Toyota

On Toyota vehicles P1625 is documented as: ECT1 signal circuit.

Related Toyota codes:

P1625 on Volvo

On Volvo vehicles P1625 is documented as: MIL output.

Related Volvo 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 P1625 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.