The Ugly The Truth About Audi G28

How to Replace an audi q3 key G28 Engine Speed Sensor

In this video Charles the Humble Mechanic shows how to replace the G28 engine speed sensor. The sensor is situated on the edge of the transmission just above the flywheel ring gear. It transmits a signal to the ECU via an uncolored wire T55/49, then to the tachometer located on 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 a signal to ECU pin T55/49 via the grey wire. The ECU utilizes this information to regulate boost and fuel. It also sends an indication to the G5 tachometer in the instrument cluster.

The sensor is used as a reference to correlate with the G40 Camshaft Position Sensor. The ecu needs to know when the crankshaft is TDC and the location of the camshaft so it can trigger spark and injectors accordingly.

If this sensor fails the ECU will throw an error code P00160 which indicates that the Crank Shaft and Intake Camshaft aren't in sync and could indicate the chain is stretched or a jump link on the upper chain of timing. However, the code won't appear on its own, without additional information from other sensors (G4 and G40).

Testing is a bit tricky since there are two pins for the connector and they serve different purposes but the most effective way to test it is by measuring resistance between the sensor and the ECU. It should read approximately 1000 ohms if the sensor is operating at its maximum. If you're having issues with this component, look replacement key for audi evidence of oil or coolant in the connector bay.

2. Injectors

Yesterday, while accelerating from the highway paytoll at a high speed I noticed a significant drop in power. It was like the engine had run out of gas. Or, my injectors weren't firing. This morning i pull out the spark plugs, three were soaked with gazoline and the 4th one was dry. When i crank the engine with no sparks, i place a tissue on the top of each hole in the injector and the 3 drenched with gazoline pop out, but the 4th one stays closed. I inspected the ground connection on ECU pins 14/55, 30/55 and 48/55. I get zero Ohm. I'm assuming the issue is in another place.

I also tried to reset the PID without success. The car is able to start if the G28 is disconnected and runs fine when it is connected, but still is experiencing intermittent misfires at higher RPM. The coolant sensor (G62), even when it is unplugged, shows an ice temperature of -49c. I also noticed that the oil gauge in the cockpit shows 2 bar but the actual pressure is zero.

I don't know what to do. I feel like i've pretty much eliminated everything else. But i'm worried that i might have missed something. Let me know should you have any suggestions! TIA!

3. Fuel Pump

The fuel pump in the g28 receives signals from the RPM sensor. The GM-style sensor is identical to the G4 and both are used in the 80, 100 200, UrS and RS2 cars so you can easily find one at a wrecking yard or from a parts store. It is easy to test them - simply put your DMM into resistance mode and test the distance between pins 1 and 2 (with the bump on the connector's edge facing upwards). They should be infinite Ohms.

4. ECU

Our 20vt turbo (3B AAN, ABY, and ADU) engines have an ECU that has to be aware of the speed and position of the crankshaft in order to make decisions regarding fuel injector timing etc. It makes use of a Crank Position Sensor G4 and an Engine Speed Sensor G28 to accomplish this. If either of these sensors go badly, you will see codes on the diagnostic scanner that could cause engine shut down.

A damaged G28 sensor could cause an inaccurate speed counter for your gearbox, a gearbox that shifts faster than normal, and/or an unfire when in the gear. If you experience any of these problems, it is likely your sensor is going bad and needs replacing. The good news is that they are very affordable and easy to find particularly when you're looking at a Bosch sensor, which is what ours are. Alternatively, GM's version of this part is an option.

5. Tachometer

A failing engine speed sensor could be the cause of numerous problems in your vehicle. It is an important part of the transmission in your spare audi key because it relays information to the ECU regarding how fast or slow the car's engine is spinning. When this sensor fails, it could cause problems for Spare Audi Key the transmission, as well as the other car's components.

The G5 engine speed sensor is situated on the outside of the transmission above the flywheel ring gear and sends a signal directly to the ECU at pin T55/49 through a grey wire. The ECU is then able to process this signal to control fuel, timig and boost as well as transmitting it to the G5 tachometer in the instrument cluster. You can test for sensor failure by examining the continuity of the sensor to the tachometer. Also, you can verify continuity between pin T55/49 of the ECU and pin T6a/1 of the instrument cluster (trace [79]), and between pin T6a/1 as well as pin T26a/12. There should be the resistance to be around 1000 ohms in these areas. This is a common part across the Replacement audi a4 Key 80, 100, 200, UrS and RS2 range from 1985 MC until the 1997 UrS AAN and 1995 RS2 ADU. Good ones could be available in wrecking yards.