P1606 — 20 documented meanings by make

P1606 does not mean the same thing on every car — manufacturers reuse the number for different faults. 18 makes document it: Audi, Chevrolet (Daewoo), Chevrolet (USA), Chrysler, Citroen, Ford, Hyundai, Jaguar, Mazda, Nissan, Opel / Vauxhall, Peugeot, Saab, SEAT, Skoda, Suzuki, Toyota, Volkswagen. Find your make below.

P1606 on Audi, SEAT, Skoda, Volkswagen

On Audi, SEAT, Skoda, Volkswagen vehicles P1606 is documented as: Poor road info/specified engine torque from ABS control unit, electrical fault in circuit. P1606 is stored when the ECU sees malfunction on ABS / wheel speed. 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 Audi, SEAT, Skoda, Volkswagen codes:

P1606 on Chevrolet (Daewoo)

On Chevrolet (Daewoo) vehicles P1606 is documented as: External WATCHDOG checking system.

Related Chevrolet (Daewoo) codes:

P1606 on Chevrolet (USA)

On Chevrolet (USA) vehicles P1606 is documented as: Serial communication problem with device 6.

Related Chevrolet (USA) codes:

P1606 on Chrysler

On Chrysler vehicles P1606 is documented as: After run.

Related Chrysler codes:

P1606 on Citroen, Peugeot

On Citroen, Peugeot vehicles P1606 is documented as: ECM control relay O/P circuit:; Malfunction indicator light (MIL) control circuit. P1606 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 Citroen, Peugeot codes:

P1606 on Ford, Mazda

On Ford, Mazda vehicles P1606 is documented as: Main relay malfunction (power hold). P1606 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 Ford, Mazda codes:

P1606 on Hyundai

On Hyundai vehicles P1606 is documented as: Acceleration sensor not rational.

Related Hyundai codes:

P1606 on Jaguar

On Jaguar vehicles P1606 is documented as: ECM control relay output circuit. P1606 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:

P1606 on Nissan

On Nissan vehicles P1606 is documented as: Engine control module calculation function. P1606 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 Nissan codes:

P1606 on Opel / Vauxhall

On Opel / Vauxhall vehicles P1606 is documented as: ECU EEPROM; Throttle control; Engine torque not plausible; Replace electronic control unit; Engine load signal not plausible; Accelerator pedal position sensor; Crankshaft position sensor A circuit. P1606 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:

P1606 on Saab

On Saab vehicles P1606 is documented as: Internal control module malfunction. P1606 is stored when the ECU sees malfunction on control module. 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 Saab codes:

P1606 on Suzuki

On Suzuki vehicles P1606 is documented as: Malfunction indicator light circuit. P1606 is stored when the ECU sees malfunction on lighting circuit. 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 Suzuki codes:

P1606 on Toyota

On Toyota vehicles P1606 is documented as: Open, short to positive or short to ground in MIL circuit. P1606 is stored when the ECU sees short to ground 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 insulation chafed through where the loom passes a bracket or edge; Water or salt in a connector bridging the signal pin to the body; The component itself shorted internally; A harness pinched during earlier repair work.

Check first, cheapest first:

1. Unplug the component and re-read the code — if it changes, the fault is in the component, not the wiring
2. Inspect the loom where it passes metal edges, brackets and hinges
3. Open the connector and check for green corrosion or moisture
4. Measure resistance from the signal pin to a body ground; near-zero confirms the short
5. Repair the harness section, or replace the component if it shorted internally

Related Toyota 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 P1606 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.