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How to Replace an audi a4 key replacement G28 Engine Speed Sensor

Charles the Humble Technician shows how to replace the G28 Engine Speed Sensor. The sensor is located near the transmission's edge, above the flywheel gear. It sends a message to the ECU through an uncolored wire T55/49, then to the tachometer in the instrument cluster.

1. Engine Speed Sensor

The sensor is located at the edge of the transmission, above the flywheel ring gear, the G28 Engine Speed Sensor sends signals to ECU pin T55/49 via the grey wire. The ECU then uses this information to control the flow of fuel, timig and boost. It also sends an indicator to the G5 Tachometer in instrument cluster.

The sensor is used as a reference point to connect with the G40 Camshaft Position Sensor. The ecu needs to be aware of when the crankshaft has reached TDC and also the location of the camshaft in order to activate the spark and injectors.

If this sensor fails, the ECU will display an error code P00160 which indicates that the Crank Shaft and Intake Camshaft are not in sync and could indicate chain stretch or a jumped link on the upper timing chain. The code will not appear without the additional information provided by other sensors (G4 or G40).

Testing is a bit challenging as there are two different connector pins, and they serve different purposes however the best way to test it is to measure resistance between the sensor and the ECU. It should read approximately 1000 ohms if the sensor is at full operation. If you're having issues with this sensor, look replacement key for audi evidence of coolant or oil in the connector bay.

2. Injectors

Yesterday accelerating full speed from highway paytoll, I experienced an abrupt drop in power like the engine is out of gas or the injectors are not firing at all. This morning i pull out the spark plugs, 3 were drenched in gazoline, the fourth one was dry. I put a piece of tissue over each injector hole and when i turn the engine on without sparks, the three with gazoline jump right out. The 4th one remains closed. I tested the ground connection of ECU pins 14,30, and 48/55. I found 0ohm. I assume that the problem is in another location.

I also tried to reset the PID without success. The audi car key cover will start when the G28 is unplugged, and it works fine when the G28 plugged in. However the intermittent misfire issue continues to occur at higher RPM. The temperature sensor for coolant (G62) shows the wrong temperature value of -49c even when i unplug it. Also i noticed that the oil pressure gauge in the cockpit shows 2 bar while the actual pressure is 0.0 when i rev the engine.

I'm not sure what to do. I believe that I've ruled everything else out. However, i'm afraid that I might have missed something. If anyone has suggestions, please chime in! TIA!

3. Fuel Pump

The fuel pump of the g28 receives signals from the RPM sensor. The GM-style sensor is the same as the G4 and they both work in the 80, 100, Replacement Audi Keys 200, UrS and RS2 cars so you can easily find one at a salvage yard or from a parts store. It is simple to test them: simply switch your DMM into resistance mode and determine the distance between pins 1 and 2 (with the bump at the connector end facing up). They must be infinite Ohms.

4. ECU

The ECU in our 20vt turbo (3B AAN ABY) engines requires to know the speed and position of the crankshaft in order to make a decision about fuel injector timing, etc. To accomplish this, it uses a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If you encounter a problem with either of these, the diagnostic scanner will display the codes that could trigger an engine shut down.

A damaged G28 sensor can cause an inaccurate gearbox speed counter and a gearbox which shifts faster than normal, and/or an unfire when in gear. It is likely that your sensor is failing and needs to be replaced if you encounter any of these signs. The good thing is that they are quite affordable and easy to find, especially in the case of an Bosch model, which is what we have. Alternatively, GM's version of this component is an option.

5. Tachometer

A failing engine speed sensor could be the cause of a slew of issues with your car. It's an essential component of the audi connect key's transmission because it communicates to the ECU about how fast or slow the vehicle's crankshaft is spinning. This sensor could cause the transmission to malfunction and other car components to be affected.

The G5 engine sensor is located at the edge of the transmission, just above the flywheel ring. It transmits signals via a gray wire to the ECU pin T55/49. The ECU then uses and processes this signal to control the flow of fuel, timig and boost, and also sends it on to the G5 tachometer inside the instrument cluster. You can determine if the sensor is in failure by checking continuity from the sensor to the tachometer. Also, you can examine the continuity between pins T55/49 of the ECU and pin T6a/1 of the instrument cluster (trace [79trace [79]), and between pin T6a/1 and pin T26a/12. You should see around 1000 ohms of resistance between these two points. This part is common across the replacement audi Key cost uk 80-100-200-RS2 series, starting from the 1985 MC up to the 1997 UrS AN and the 1995 RS2 Du, so you might find good ones in wrecking yards.