How to Replace an audi replacement audi a4 keykey audi service (https://tastewolf37.bravejournal.Net) G28 Engine Speed Sensor

Charles the Humble Technician teaches you how to replace the G28 Engine Speed Sensor. This sensor is situated on the outside of the transmission just above the flywheel gear. It transmits a signal to the ECU via the grey wire T55/49 and then to the tachometer on the instrument cluster.

1. Engine Speed Sensor

Located on the edge of the transmission just above the flywheel ring gear the G28 Engine Speed Sensor sends a signal to ECU pin T55/49 using a grey wire. The ECU utilizes this information to regulate the amount of fuel and boost. It also sends an alert to the G5 Tachometer in instrument cluster.

The sensor is used to connect with the G40 Camshaft position Sensor. The ecu needs to know when the crankshaft reached TDC, and the location of the camshaft to trigger the spark and injectors.

If this sensor fails the ECU will show a P00160 code which means the Crank Shaft and Intake Camshaft are out of sync, possibly indicating chain stretch or a jumped link on the upper timing chain. However the code will not be displayed on its own without additional information from other sensors (G4 and G40).

Testing can be a bit difficult because there are two connector pins, and they serve different purposes but the best method of testing it is by measuring resistance between the sensor and the ECU. It should read around 1000 ohms if the sensor is in full operation. Check for signs of coolant, or oil in the connector bay if you have problems with this part.

2. Injectors

Yesterday, while accelerating at full speed from the highway paytoll i had massive power loss like the engine is running out of gas or the injectors aren't firing anymore. Today, i pulled out the spark plugs. Three were soaked with gazoline and the fourth was dry. I put tissue over each injector hole, and when i turn the engine on without sparks, the three with gazoline jump out. The 4th one stays shut. I checked the ground connection on ECU pins 14/55/30/55/48/55/14/55/48/ I got 0ohm. So i assume the problem is in another place.

I also tried to reset the PID without success. The car will start if the G28 is unplugged and runs fine when it is connected however it has the intermittent misfire issue at higher RPM. The coolant sensor (G62) even when it is unplugged, shows a temperature of -49c. Also, i noticed that the oil pressure gauge in the cockpit is showing 2 bar while the actual pressure is 0.0 when I crank up the engine.

I don't know what to do. I feel like i've pretty much ruled everything else out. I'm afraid i may have missed something. Please let me know should you have any suggestions! TIA!

3. Fuel Pump

The fuel pump in the g28 is activated by a signal sent by the RPM sensor. The GM-style transmitter is similar to the G4 sender and both work on the 80,100,200, UrS, and RS2 vehicles. It is easy to find an extra in a wrecking shop or a parts store. Testing them is easy by putting your DMM in resistance mode and take measurements between pins 1 (with the bump on the connector's end up) and 2 (2nd from the left on the black connector's end). They must be infinite ohms.

4. ECU

The ECU in our 20vt turbo (3B AAN ABY) engines needs to know the speed and position of the crankshaft to make decisions regarding fuel injector timing, etc. To do this, it uses a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If you encounter a problem with either of these sensors, the diagnostic scanner will show codes that could cause an engine shutdown.

Some of the signs of a failed G28 sensor include an inaccurate rev counter in the gearbox the gears are shifting faster than normal, and/or a misfire when in gear. It is probable that the sensor is failing and needs to be replaced if you notice any of these signs. They're cheap and easy to find especially in the case of an Bosch sensor like ours. Alternatively, GM's version of this part is an option.

5. Tachometer

A failing engine sensor could cause a myriad of issues within your vehicle. It's an essential component of the transmission of your Audi because it relays information to the ECU about how fast or slow the engine is spinning. If this sensor fails, it will disrupt the performance of the transmission and the other car's components.

The G5 engine speed sensor is situated on the edge of the transmission above the flywheel ring gear. It transmits a signal to the ECU at pin T55/49, via an uncolored wire. The ECU is then able to process this signal to regulate the flow of fuel, timig and boost, and also sends it on to the G5 tachometer inside the instrument cluster. You can check the sensor for failure by examining the continuity between it and the tachometer. You can also check continuity between ECU pin T55/49 and the instrument cluster connection on pin T6a/1 (trace [79]) and between T6a/1 and the instrument cluster pin T26a/12. There should be an average resistance of 1000 ohms between these two points. This part is common across the audi key programming 80-100-200-RS2 series, starting beginning with the 1985 MC and up to the 1997 UrS An and 1995 RS2 DU So, you may find some good ones in wrecking yards.