P1993 — 3 documented meanings by make

P1993 does not mean the same thing on every car — manufacturers reuse the number for different faults. 6 makes document it: Audi, Opel / Vauxhall, Saab, SEAT, Skoda, Volkswagen. Find your make below.

P1993 on Audi, SEAT, Skoda, Volkswagen

On Audi, SEAT, Skoda, Volkswagen vehicles P1993 is documented as: Exhaust gas recirculation potentiometer 2, G466, signal too strong. P1993 points at EGR system. The standard definition names the system involved; which part inside it has actually failed is what the checks below establish, cheapest first.

Usually one of: Valve stuck with carbon deposits; Cooler blocked or leaking; Vacuum or electrical control fault; Position sensor reading wrongly.

Check first, cheapest first:

1. Remove the valve and inspect for carbon — cleaning fixes a large share of these
2. Command the valve with a scanner and watch whether it moves
3. Check the vacuum line or electrical connector depending on the type fitted
4. Replace the valve if it will not move when commanded and cleaned

Related Audi, SEAT, Skoda, Volkswagen codes:

P1993 on Opel / Vauxhall

On Opel / Vauxhall vehicles P1993 is documented as: Gear ratio incorrect in D and R range. P1993 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 Opel / Vauxhall codes:

P1993 on Saab

On Saab vehicles P1993 is documented as: Gearbox slipping in gear 1 or R. P1993 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 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 P1993 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.